There is absolutely no reason she can't talk to travel ball coaches about her availability this coming season. She will violate no NCAA rules with that conversation. She should check with her college coaches but they will be very supportive of her getting back in game shape. (They may know a team that is looking)
Most TB tournaments will occur after the College season is over and should not be in any conflict with TB. The college players will not be able to make most TB practices because of the overlapping of the seasons and the practices. The college players will be getting more practice time, lifting and game experience than most for the TB players and should show up for TB-game ready.
She should go over the OFC list of teams looking for players and make contact now. If she waits for her college season to conclude and the TB season to start she will be lucky to land on an acceptable team but may just be able to guest for a few weekends. If she is looking to be a full fledged player on TB team then she should make contact now and get a situation solidified.
Make sure that the team she selects has similar desires. She is already in college and on a college team she will not need to go a bunch of showcases or even a world series tournament. Playing a gold schedule doesn't make much sense. She will be coming off a 40 game season with practices every day, so running to 10 summer tournaments may not excite her. She will also want to hangout at home and see some high school friends so traveling long distances to spend weekends away may not interest her. Likewise paying TB fees for extensive indoor practice facilities doesn't make much sense for a college player.
There are still a number of 18U teams that are looking for that last player and she just might fill the bill. Good Luck