[jyl]

Not much difference in recoil, between 9mm and 45cal, the pistol design and weight make more difference. Bigger, heavier pistols kick less, all else equal.

Single stack magazine may be better if she has smaller hands. Similarly, she needs to be able to reach and operate controls - safety, decocker, slide release, lower hammer, etc - without difficulty.

Glock has simplest operation; others are simple too; 1911 may be the most complex. Pertinent if she's not going to practice with it regularly.

She may lack the hand strength to easily cycle the slide. It needs to be almost effortless for her, even with wet hands or other imperfect conditions. Using weird grips, or pointing gun in odd directions, or bracing the gun on stuff, as she struggles to pull the slide, is dangerous. In that case, you might consider a revolver instead. Six rounds of 357 Magnum should really suffice. Presumably she doesn't have delusions about getting in long firefights and combat reloading and other ridiculous mall-ninja fantasies.

If this is for concealed carry, then I am a fan of snubnose revolvers. .38 SPL doesn't kick too much.