Help please.

How we understand NeuroTypical individuals and how they understand us is always interesting. 

I can see how someone who is in a complete state of confusion, never connecting with anyone, continually feeling dismissed, disregarded, ignored and as if everyone is speaking in a secret code can become aggressive. They can feel a deep sense of injustice and if they have any kind of moral back bone can feel a bit of a righteous anger in an oppressive society. 

If there is a stigma around Spectrum/Autism because no one has been told it is simply a different way of perceiving and experiencing and communicating in the world not a disorder but a difference, than it might be hard to bring it up. I might suggest you buy a book called A Field Guide for Earthlings. Read a bit and bring it to her telling her you tried reading it for something you're working out but perhaps she can make better sense of it? A physical copy is easier for most of us to read than digital screens. Anything unnatural can be a source of pain when exposed to it. 

One of the best ways for us to recognise being Autistic is by being exposed to others who are also. Just as most in society have a sort of social fluidity and feel generally understood, Autistics only experience this around each other. We have empathy for one another just like NeuroTypcial society has empathy for each other. NT to AS is where Relating With and Intuiting the Other becomes a problem (these being the sociological definition of 'Empathy').

Yes she does often feel like this, she will say so and so is staring at her therefore she will do it back or ask them if they habe a problem. But to us it will be a security guard on duty watching all the customers. I will look into this book and try giving it to her. We have mentioned autism before to her but she got very upset and angy so wanted a tactile way of doing it.

Gosh, I have to say it's taken me about 4 times re-reading what you've written to comprehend what you mean. Perhaps you wrote it fast? It's something Autistic beings need a overwhelming amount of help with. But in society, it's good to note, most NT individuals are so used to others reading their mind or reading into their sentences that they forget we need a little extra work to communicate with precision with each other :) 

One of the best things we can all do for each other is engage further. If you see a security person and your sister feels invaded, it's worth having a chat with her about the issue itself. For one, Dominating other humans is a big part of NeuroTypical culture. You may not be too bothered about this, but she may need to consciously understand how the Social Hierarchy works and how it can make individuals obsessed with Power. Oddly, understanding the structure can make her feel much less bothered by it. it is usually a lack of clarity and a lack of understanding WTF is happening in the world that creates a great deal of intensity. 

This understanding of the mechanics of Power is not just from an Autistic point of view but has been explored for hundreds of years in philosophy books to psychoanalytic books. Michel Focault was famous for explaining Theories of Power. Your sister is not wrong. Humans will find their way into the police force or army for the love of power over others. 

If she enjoys research, he might be a good philosopher to buy her. But I would engage the issues within the exchange. From both your point of view and hers. It is better to explore and exhaust these things and help her discover she's not wrong, she's just thinking from such a different part of her brain about it all and not able to switch off like everyone else. These clarities of differences can also lead her to discovering the Autistic brain and it's amazing technicalities. Embracing the self is much better than being sliced off from the collective and marginalised. 

This is such good advice Juniper - I heartily agree. 
I think it’s clear that your sister is feeling threatened and highly anxious. This may or may not be valid objectively - but to her it undoubtedly feels that there is a sense of threat emanating from many of the people around her. 
I think you need to talk to her about what makes her feel that way, and help her to feel more safe in any way that you can. I really feel sorry for her she is obviously severely anxious and must be in a lot of psychological pain. Would she speak to her GP about getting some counselling? Or might that be too much for her? Does she have anyone else involved in her care?

This is such good advice Juniper - I heartily agree. 
I think it’s clear that your sister is feeling threatened and highly anxious. This may or may not be valid objectively - but to her it undoubtedly feels that there is a sense of threat emanating from many of the people around her. 
I think you need to talk to her about what makes her feel that way, and help her to feel more safe in any way that you can. I really feel sorry for her she is obviously severely anxious and must be in a lot of psychological pain. Would she speak to her GP about getting some counselling? Or might that be too much for her? Does she have anyone else involved in her care?