I am real surprised on all the different choices that were mentioned, some of which I would shy away from, and some that I would go for.

RedLion asked about a pistol that has stopping power and not break the bank. Personaly in a semi autoI would not go with anything less than a 9mm and the 9mm would be a conditional buy for me. They are nice because of the size of the cartrage and you can carry more. I would look into a 40s&w or a 45acp for the real stopping power.
In a revolver I would go with a 357 mag due to the fact that it can be shot with 38's for learning and practice and not break the bank on a box of ammo.

As far as making a suggestion I would suggest going to a gun shop and looking at several diffrent handguns and see what feels best in her hands. Lets face it the gun that fits her best is going to be the most enjoyable for her shooting.

Shane