How do I help my adopted brother?

My brother got adopted to my adopted family, he is 37 year old and has autism, my dad found out today and he is staying with us, my dad wants treatments for his autism, he flaps his hands, says the wrong things and cannot initiate or sustain a conversation, my dad wants to treat these symptoms but how do we. His autism is mild as the doctor said and he may never be able to live alone unless he receives treatment and he is jobless as well, he has no job or friends, how do we help him. My dad says we are going to have to send him to the hospital to work with someone on his symptoms, I asked the doctor if he could ever live on his own and he said to me "Give up." and I replied with "What." "There is no hope." I left in tears who can help him, he has clear speech and no speech impediment but has difficulties in communication how can we help him. After I said "What." and left in tears I went back to the doctor and he told me "It's to late, there's not much we can do?" I left again, maybe we should give up and that there is no hope.