How old is she? If she's young, then just tell her that she'll probably grow out of it, because she's young and she probably will. There are many risks in UFC, for one, both people usually bleed a lot, two, blood + blood usually results in disease, two, wounds, and lastly, it's a lot of work. Overall, if you really want her to, put her in an MMA class, they're getting pretty popular now, and it isn't difficult at all to find one.