Is it permissible for university employees to take "success sweets" or any money from students after exams or the announcement of results in exchange for their help?

It is not permissible for workers or others to beg people for money unless they are in need and are among those for whom begging is permissible. These are: one who has taken on a debt [to reconcile people], one whose property has been swept away by a calamity, and one who has been afflicted by severe poverty and has had it attested to by three people from his community. Anything other than that is forbidden. As for giving them money as a gift, it is permissible, even if they are not among those for whom begging is permissible.