Take her to the store with you and let her pick out the one that she wants and is comfortable with (grip, trigger pull, etc).
^^^This^^^ if it fits her small hands well! she is a lot more likely to practice with it.
Personally, I always suggest revolvers for new lady shooters.
No jams, no safety's, and no mags to keep up with. Hard to beat a 3" J-Frame if she doesn't plan to carry it on her person, or even a 4" K-frame. Also if you find a deal on one, the old Ruger Security Six or Speed Six make great house guns and have small grips that usually fit women well.
Buy her some target Wadcutters for practice and load it up with Speer Gold Dots for defense.
