Mrs. RRASH loves the 9mm 3.8 XDM. It is a great gun.The Annoyed Man wrote:Springfield XDS-9mm would be worth a look, if you're limiting yourself to single stack guns. If double stacks are under consideration, the XDM-9mm 3.8 Compact is an impressive gun, and very soft shooting.
My advice would be to narrow down your selection to 3-4 options, go to a range that would rent these out to you, and make a date out of it. I know a 9mm is going to be better than a .380 on paper, but even that boils down to what gives her confidence - not only in accuracy and recoil management, but concealability, draw, clearing malfunctions, reloading, etc. If she isn't comfortable, she won't carry, and even a .32 is better than pepper spray.