Here you go, I found this web site for you. They have many different types of phones that you can use this application with. They have the application already preloaded on phones if you don't want to load it your self.With this system you can monitor her on the Internet or I believe over your own phone. Neat idea they have, so you may want to check it out.
What a concept/what a plan to be able to keep your eyes on her at all times. Just don't let her know that you're getting it for her. So that she doesn't lose her phone.
Best of luck to you, I really hope that this helps you out.