I'd go with a 4-inch barrel and any of these will be just fine for her needs. Ruger's GP100, Service-Six or Security-Six, Colt's King Cobra, Python and S&W's models 66 or 686 and 686 Plus. The "plus" has a seven round cylinder. There are more choices like Taurus and some others, but the above would be my personal choices. I'd take her to a gunshop and see what fits her hands the best and go from there.