I always recommend a hammerless revolver. They work inside of pockets, they work inside of purses...they work every time.
Always good advice to "work up" to the target load. Nobody likes to get the crap kicked out of them unexpectedly.I have little experience with carry guns, except for the Ruger Redhawk .44, but the best advice I've ever heard on the subject- for both men AND women- is to start them out with a .22 (or .22 Mag) until they get VERY proficient with that. THEN move her up to a centerfire and I'd look at a 5.7x28.
Small guns are harder to shoot and the slides are harder to operate. These guys have given good advice.This right here! And as others have said and suggested, get her to a range that rents or allows you to try different pistols as possible. Comfisherman made some good points also. Fit and ease of function is everything with a pistol for everyone especially female. Also consider wrist strength when at the range trying them out. Once the wrists get a little weak the form and accuracy will go to xxx and the fun stops. Unless shes used to shooting a pistol, 50 or less rounds is probably enough for the first couple trips. For and from the females in my family recommendations are S&W EZ 9 or 380, Springfield Hellcat, Sig 365.
The key to being proficient with a firearm- ANY firearm- is practice.Always good advice to "work up" to the target load. Nobody likes to get the crap kicked out of them unexpectedly.