Revolver may be best for someone with limited hand/arm strength. Also the Ruger cylinder latch with its large push in lever manipulation may be easier for her also.
While alot of revolvers can be had in a lightweight frame, most of the still have a very heavy trigger pull that would make it difficult an elderly woman to shoot accurately. A good set of springs and a good polishing would help alot, but in my experience, the old "revolver for women and elderly" adage is outdated. She would be better served with a good dog, and a phone holder on her walker. Granted the manual of arms is what makes revolvers an easy choice for women and elderly, but the heavy trigger pull and muzzle blast make them not a good choice in alot of instances.
The Shield EZ is what I would recommend if she really wanted a gun. Both the .380 and 9mm are very easy to manipulate for the average female, but if she does not understand how to run it, it's a non-starter.
JM2C, YMMV.