@Torahmom – I wish I knew what to tell you. It’s a tough call, but if you know that she’s not a reckless websurfer while she’s living with you, whether inside or outside of your home, I wouldn’t worry so much about other seminary girls being a bad influence on her when it comes to Internet access.
Just playing devil’s advocate here, but how do you figure she will contact you while she’s away? Calling long-distance can cost a lot of money, so you might want to consider email.
Good luck making the right decision for her. I think our fellow posters here have raised some interesting points.