So Undercover (2012)

Molly is a teen who works with her father, an ex-cop turned P.I. One day an FBI agent approaches and wants her to work for them. They want her to keep an eye on the daughter of a man who is about to testify against a criminal. So they send her to the college where the daughter is attending, and she tries to fit in while keeping an eye on her and trying to see if anyone there isn't who they appear to be.