I'm so sorry to hear what your are going through. I have a mentally retarded brother, and may parents encountered some of the problems you are facing from the gov.(very little help if you are the parents, but more help if someone else cares for him)
He was in various places and was very unhappy. He kept saying he just wanted to go home. Finally one of the social workers suggested that my parents become a part of their system and my brother could live with them and they would get the help too. So that what they did, they became licensed care providers and took care of their son. Of course there was visits by a several people, making sure they were running things by the book. My Dad got so he enjoyed talking to the different ones. They did take a few others in from time to time temporairily too.
I don't know if this will help you but you might look into it. Hope things get better for you.
Sadie