Sorry in advance for being blunt, but if anyone responded to me that way, I would do what ever possible to make sure they are no longer an important part of my life. Your family is the people who love and support you no matter what, and not neccesarrily actually related to you. I don't mean completely cut them off, but don't be in a situation where you have to rely on them. (I realize this can be difficult with parents... I went 3 years without talking to my parents more than once every 3-4 months)
I'm assuming though, since your friend has to ask his mom to buy him a binder, that your friend is under 18, and can't support himself yet. I know it sucks, and hate to suggest it, but he may just have to go along with what his mom wants (and keep a roof over his head) untill he can get a job/ move out/ not have to rely on her anymore.
That being said though, it probably won't hurt to try to educate your friends mother though (but don't be obnoxious or confrontational about it. I'm not anywhere near florida, so I have no therapist suggestions.