I'm going to be the slightly contrarian here. Take her to a range that has a LARGE selection of rental guns and figure out what she likes and dislikes about different models. Then look around at different instructors and see if she can take a basic pistol class and if the instructor has any of those models to borrow/rent during the class. A woman's class would be even better.
Manipulating the slide and firearm in a tactical/defensive scenario is different that on a standard shooting range. That way she isn't learning any bad techniques about shooting or manipulating the firearm, and he/she may know some tips that work better for women. For example my wife cannot slingshot a slide in the same way I can at all. However, the technique she was taught at the Faster classess works great for her.
I would caution against a revolver. They have the simplicity of action in their favor yes. But they have a lot of things against them. The long double action trigger pull is challenging to be fast and accurate with. The limited capacity is a hindrance against someone who is chemically enhanced or against multiple threats. Running lightweight loads decreases felt recoil but also dereases effectiveness.
The .380 ACP is a bare minimum round. The P380 by sig or the colt mustang is a great gun but it has a manual safety that you have to train to remember to disengage. It'll probably take multiple shots with a 380 to achieve the same stop as a 9mm.
There's a reason most law enforcement has moved to the 9mm. Easy for most people to shoot, economical to shoot and the same size gun carries more rounds than in the other common calibers of 40 or 45.
A smaller frame gun may or may not fit her hand better but will have more felt recoil and less rounds carried. Also, the recoil springs are stiffer than the larger size in the same gun making it harder to manipulate for reloads/malfunctions or in general.
My wife carries a S&W Shield but I also had to do some slight sanding of the frame to fit her hand and not cause blisters on higher round count classes.