Planning to send my autistic brother to USA to avail of better medical support, PLEASE HELP.

Hi, my name is Kim and I'm from the Philippines. I have a low-functioning autistic younger brother. He's 21 years old now, refuses to get dressed and so he is naked, for almost two years now. His routine does not include regular bathing and bowel movement, making our house smell really bad not just for us but for our neighbors. I really feel bad for my grandmother who stays at home to take care of him. 

Meanwhile, my father and mother are separated. My father is now a US Citizen and tells me that he would petition my brother to live in the US so he can be better taken care of by professionals there. But he doesn't know how. He is not familiar with the process.

Can anyone please provide me with information as to how to go around with this concern?

My father already knows the petitioning process. However, he worries about how my brother would be taken care of in the US. He is also concerned with how to get my brother on the plane without him throwing a fit or tantrums.

Before my brother goes to the US, particularly in California, what are the steps that my father has to take care of? What agencies could he ask for help or assistance?

I really appreciate your kind and helpful answers. 

Thank you very much.