Well, I think it would be fine to say, "I don't think doing homework at the library is working well for you right now." And I do think it's appropriate to go over, "So, it's not considerate to be loud and distracting in the library," although I bet she darn well knows this, so IDK. (You know, TBH I haven't been to many libraries where it was stone-quiet; some child, adult, or homeless person is periodically loud at ours on a very regular basis). But I wouldn't want to see this turn into a shaming, "No public places for YOU! YOU can't CONTROL yourself!" thing, not that I think the OP will. It's more that I read a post like that and feel sad and wonder how many people are thinking that sort of thing all the time about children with challenges, emotional or otherwise ("They should not bring that child in public!")
