Ruger LCP, .380, with Speer Gold Dot ammo.
Or the original, Kel Tec P-3AT.
You might want to have the "Smaller guns focus the recoil more" conversation. I find women are drawn to smaller guns because they are less intimidating, but they also hurt. The 'logic' of the small gun is flawed...
I hate shooting my P-3AT. It hurts. After getting around the psychological factor of it, I've had no woman disagree. Small gun for concealment, sure. But if you want to shoot it, get something bigger.
My Mom kidnapped my Glock 31. She tried to take my 1911, but noooo. Not even for Mom!
The P9 has a fuller grip and is still pretty small. But the P9 you need to know the history of. It's the gun that gave Kel Tec a bad rep... It's straightened out now, but you want to be sure it's a new one. The old ones suck.
Don't buy anything before she shoots a few. Rent some if you can't borrow them. Get her to try out the 'scary' guns. My son's 8 year old friend, scrawniest 8 year old you ever met, loved my 1911. Hold it like you mean it!