On what ground her visa is rejected because the Embassy must have told the ground for her rejection.  If they rejected because they thought she missed her studies than ask her to request a letter from the University that she has taken a leave and University were fully aware of the situation. I think a letter from University regardig this might solve her cause. But i am not so sure.  Also let tell her , getting visa rejected is not the end of the world. Several people gets visa rejected. Most of the times it happens because you cannot provide proper documents.