D..
What the heck? Your husband denies there's a problem and his family wants her institutionalized? There's something very wrong here.
You need to have this child evaluated. Your husband doesn't know what he is talking about. Perhaps it isn't autism, but there is something terribly wrong.
I don't know who you have talked to, but she has not had a proper evaluation if the school is just moving her from grade to grade when she is doing kindergarten level work.
You had better write the school a letter and send it certified to the head office telling them that they need to evaluate your daughter for learning disabilities. By law, they have to answer you within a certain amount of time, and they have to have a child psychologist evaluate her. I would stop going to the school every time they call you over her bad behavior. They are responsible for her while she is there - not you. The guidance counselor should be handling her.