+1000 to the earlier person who stated that you should find a range that will rent and allow her the chance to try lots of different firearms to find out what she is comfortable with.
When we started shooting, my wife really liked Glocks. And kinda decided she'd like a 19... but could not *consistently* rack the slide and lock it back. We then went to the sales counter and one of the salespersons walked her through *every* 9mm semi-auto they had in stock.
She determined which ones fit her hand and which ones she could consistently operate. We wound up renting a Beretta PX4 Storm, which she found very easy to shoot and manipulate. Additionally, the backstrap can be changed. She put the small one on her gun. She qualified with this gun and is very accurate and consistent with it. Hell, she's consistent and accurate with my Glock 23! I'll be her backup anyday!
Since then she's also collected a Bersa Thunder and a Walther P22 that she absolutely enjoys... although she's decided she's a revolver collector. I'm not worried either way.
In the final estimation, let her operate or rent everything she can and make her own determination. Not only does it fit her need, but it makes for greater safety as well.