It would make the most sense for her to have her own policy since she will be traveling, and potentially living, in multiple states after no longer being considered a student. Her "home address", as far as an insurance company is concerned, is where she keeps the vehicle for at least 6 months out of the year. So if she will only temporarily be living in those other places then she should use the address where she'll be living more permanently. She should consider shopping around
with as many companies as possible to find the best rate, regardless of where she ends up.