Have I done something wrong?

I totally agree that sending a sympathy card apologising for what you said, offering your condolences and saying you're there for her would be a good idea. That would be less invasive than messaging/phoning etc at this time, but would show you're thinking of her. And yes, be kind and gentle to yourself. We all make mistakes, especially when we're struggling with grief.

I agree with what other people have said here. I’d just add though that please be forgiving of yourself for making a mistake regarding these comments to your friend - because you didn’t mean to upset her. You’re grieving too so it’s a highly emotive subject for you. If I were in your position I would send a card simply saying  ‘I’m sorry, I got this wrong and I’m sorry that I hurt your feelings at a time when you needed support. I’m here for you whenever you need me and I’m so sorry for your loss’. 
Give her time and space as people have said above, but at least the card will make her aware that you’re sorry and that you’re here for her. Hopefully she’ll understand. Good luck, and I’m sorry for your loss. 

I think this is great advice from Giraffe. And the line from the poem is wonderful and relevant to many sensitive situations we might find ourselves in when we need to be present for other people when they are struggling. Who is the poem by? I’d like to read the whole poem. 

Firstly, my sympathies to you on the recent death of your grandfather. 

As others have commented, I'm inclined to think your grief has possibly influenced your opinion toward your friend and her family. Everyone is different in terms of how they offer support when it is known that a loved one is dying. It's possible that maybe your friend's grandfather didn't want anyone other than his wife to be at his bedside when he died. From what you've said, the family had been popping in and out prior to his death.

Even when death isn't unexpected, not even medical professionals can state with certainty when the moment of death will occur, and sometimes the person themselves doesn't want to die when their loved ones are around.

Speaking from experience, I was physically and mentally exhausted when my dad died a few years ago. During the weeks leading up to his death, I'd had very little sleep, and at the moment of death, I had been awake for more than 24 hours. There was no way that I could have remained by his bedside indefinitely. To be honest, I think he had been holding on for as long as he could in the hope that we would quite literally leave him to die in peace.

As emotions are clearly running high, perhaps allow some time for the dust to settle and then see if your friend is willing to accept an olive branch. 

From reading the post I think it sounds like the friend and her family were there for the grandparents, that they lived nearby and were going in and out of the house to support them? Just because they weren't there at the moment of death, it doesn't mean that they weren't there while OP's friend's grandfather was alive.

And in my opinion, it's not for us to comment on how other families operate unless there's abuse going on and someone needs to be helped, and there is absolutely nothing here whatsoever to suggest that that was the case in this situation. Whilst I acknowledge that OP's own grief may be playing a part, their friend is Autistic too and grieving. Let's not be cruel or judgemental or think the worst, especially regarding a grieving fellow Autistic person who we don't even know.

the truth hurts, your friend can probably see that her family wasnt there for the grandparents thats why she started making excuses... all that stuff about wanting life to be normal and about how they grieve and all that stuff... thats all excuses.... excuses which tells me she knows in her mind your right about that and they wasnt there as much as they should have been and is now making excuses and denying it to make her feel better about it.

it probably is better to back down from the subject though as it will be sensitive and that truth can make her feel guilt even more than she may already do and perhaps she is trying to smother the guilt she feels.

I want to start by saying that I acknowledge you lost your grandfather recently too, that I'm very sorry for your loss and I think that maybe your own grief is playing a part in this. I have to say that my first reaction to reading this was to TOTALLY understand your friend's point of view here and think you were being very unfair and inappropriate, and wondering how the way your friend's family chooses to respond to their situation is your business, but I think the reason this seems to matter to you so much is that you're grieving yourself. I think sometimes when we're in grief - and when we're Autistic - we can get a bit of tunnel vision, and think that our way is the only way. As others have said, though, grief and coping with loss isn't like that. Every person deals with it differently, let alone every family.

Regardless, I think you know you've messed up a bit here. None of us are perfect though, especially when emotions are high. Chalk this up to experience and give your friend space to grieve, to be really honest, I don't think she even needs your apologies right now, because she might be more distressed if you keep pressing the issue when she's said she doesn't want to talk, or she might feel pressured to make you feel better - either way it really wouldn't be fair on her. Respect her wish that you leave her be until after the funeral, then, depending if you know when the funeral is or not, maybe reach out to her afterwards, saying you're really sorry and that you know you made mistakes here, and you'll make it up to her somehow (by that I mean by really trying to put yourself in her shoes and be compassionate from now on). There's a very powerful poem about communicating with people who are grieving, and there's a line in it: 'you are here to listen, not sing'. Maybe remember that in the future when you're dealing with similar situations. Take care and once again, I'm sorry for your loss.

I’m sorry this has upset you. I can also understand why your friend seems to be upset by what you’ve said to her - because you are being very critical of both her and her whole family. You’re being quite judgmental. I get the impression that she loves her family and that they had their reasons for doing things in the way they did. of course you are entitled to your opinion but in a situation as sensitive as this I think it would have been better not to share your negative thoughts about your friends actions. She is grieving and so will be feeling extra sensitive and protective of her family. 
I would recommend that you send your friend a card apologising for anything you might have said that could have upset her at this very emotional time in her life. She is bound to be feeling quite upset and vulnerable so I’m sure she will appreciate a card that is compassionate in it’s wording. 
All families are different and we all grieve in our own way. What none of us needs is having friends being judgemental of us at a time when we are emotionally raw. So I think an apology is in order. I’m sure you didn’t mean to upset her but you obviously did. Maybe send her some flowers too - I’m sure she’d appreciate the gesture. 

But did they know he was going to pass away then that evening? People can’t sit at a bedside for days or weeks without leaving it’s just not reasonable especially for an entire family to do that. I happened to be at my Grandad’s passing by chance because my usual plan for the evening was cancelled and I happened to be visiting him when he passed away somewhat unexpectedly. My Mum, aunt and uncle were also there. I was heavily pregnant and very unwell with a nasty virus when my Nan died so I stayed at home and my Mum phoned me in the morning to say she passed away. Just because your friend didn’t say before that her grandparents wanted to be alone doesn’t mean that wasn’t true. My uncle and aunt were alone together in the hospice when my aunt died and it was a very peaceful experience for them together. Just because your family did or experienced something a certain way doesn’t mean that everyone else has to do exactly the same. I have this with my husband quite a lot he can’t always grasp that different families grew up differently to him, what he did and his parents and brothers and sisters did wasn’t some sort of unwritten law that everyone in the world does. Especially when it comes to death and grief people experience and deal with it in very different ways and you have essentially told your grieving friend that you think they didn’t give a F about the dying grandfather, at least that’s highly likely how they interpreted what you said 

Thank you, absolutely, I think I need to give her space. I've been too focussed on myself here but I do stand by that her grandfather wasn't treated well by her family. If you know a family member is going to pass away you should be with them, not off having dinner or sitting at home.