Hi, and welcome to THR.
As a woman, I can tell you that guns that fit my husband do not necessarily fit me. He has, for example, a 5" Springfield 1911 that is just too big for me to shoot, despite having pretty large hands for a woman. But I can shoot my Kimber Ultra Carry (a compact 1911) just fine. I can also tell you that revolvers can be difficult if a person (male or female!) lacks the finger strength and hand strength to hold the revolver steady while pulling the double-action trigger. One can cock the hammer and shoot SA, but in a HD situation, that may not be possible.
Many people will tell you that women lack the strength to rack the slide of a semiauto. That is actually rare, particularly if she's taught different ways to do it. However, it is not at all rare for that DA revolver trigger to be hard to master. Just a caution.
My first handgun was a Springfield XD-40. I traded it for a HiPower and I am very glad I did. The HiPower is classy, accurate, easy to shoot, and makes me look more talented than I am at the range
I also have a J-frame snubbie, and my Kimber Ultra Carry; those two are my concealed handguns and the Kimber is always on my bedside table when I go to bed.
While I know this is supposed to be a Christmas present (you get MAJOR good husband points for that as a Christmas present, lol!) she needs to pick it out herself. At least take her shopping and let her figure out which one fits her hand best. If possible, find a range that rents guns so she can shoot several. But at least shopping and trying the grip on different guns, being shown how to disassemble it for cleaning, checking whether racking the slide is ok, etc., is something she needs to do herself.
Also, both of you check out
www.corneredcat.com for more info on finding handguns that fit you and other good things.
Happy shopping, and happy shooting.
Springmom