If trigger pull is an issue, try a Kahr K9. With standard pressure loads, it shouldn't kick too bad, and the pull on a Kahr is second to none, IMHO, in pre-stressed double actions. It's fairly long, but it is silkity smooth and light. If I could afford one right now, I'd have one.
The J-frame is a lot of trigger, and I wouldn't feel bad if I were her. It wasn't until after I started powerlifting routines that a J-frame trigger felt normal. Another option would be a .32, but practice ammo is pricey. If you go with a .380, look at locked breach designs, and stay away from straight blowback. The straight blowback tend to make a .380 feel like a 9mm, not to mention the slide is harder to cycle manually. Unfortunately, your selection is pretty limited comparatively.
Something like an EMP would be an option as well, provided it is hand strenght and not arthritis that is the issue. The 1911 design in a compact, 9mm offering would have a light trigger and good accuracy. You say she is familiar with firearms, but her hand strength is not good. Can she reliably rack a semi-auto slide?