I'm all for college dorms, at least for the first year. Definitely something everyone should experience, and I find that people who just stay home after high school never end up maturing the same way someone who went to the dorms does... Personally, the year I spent at the dorms completely changed the way I thought about almost everything, especially the way I dealt with people... I also came out of it with tons of new friends, which is a plus. Living in the dorms is also really the only way to become involved in school/club events, and she should at least participate in those for the first year... I commute now, and it's definitely a hassle to participate in any club meetings or events, since they all take place in the late evening.
As for religion in the dorms... Obviously she won't be surrounded by Muslims if this is an American school, but I think this has some benefits. Too many Muslims are closed minded because they haven't spent enough time around those of other faiths, and they become totally ignorant of the different people/ideas around them. The university/dorm experience will allow her to really think about other faiths, including her own, and to really build a deep understanding about it... I actually starting becoming serious about Islam in the dorms, and became stronger in faith because of the fact that my beliefs were actually challenged... ( I miss all those religious debates between me and my floor mates..

Good times...)
If you're worried about mixed gender, just make sure she applies for a floor or building that is
all girls. Most universities have this kind of set up for those who ask, and she can even request to room with a friend she already knows. It's going to be up to her to be more responsible though, since even if she commutes from home, that's not enough to stop her from being exposed to shamelessness... That part is going to be on her, but as long as you've already talked to her about certain things, and visit her/keep in touch often, it should be fine.