Wrong forum I know but I think a moderately weighted .357 magnum revolver is a great starting point for everyone. Begin with shooting .38 spl and work her up to stronger loads. Once she has mastered the basics of handling her revolver, try her with a semi-auto. Glock, XD, Sig, whatever fits her hand, chambered in 9 mm or .40.
Sorry to disagree with others, but .22LR is not the way to go or else she will never learn to manage recoil.
And don't be amazed if she becomes a better shot than you.