I'd frankly try to talk her out of a 3" by both explaining the impulse physics of the design where shorter slide/barrels have much more critical timing requirements and therefore are much more susceptible to malfunction, and the fact that it's the frame grip size that is more important than slide length for concealability. I'd want the most reliable package for her and a 3" isn't it.
I see the Colt Defender/New Agent, Dan Wesson CCO, and Brown Kobra Carry LW as options.
