What is she going to do with it? Concealed carry? Home protection? Target shooting? All of these? Each purpose has consideration factors, and while there may be overlap, the order and impprtance of factors changes.
For carry, light weight and knock down power might be the top factors. For target shooting, adjustable sights and a longer barrel might be a factor whereas knockdown is not a factor.
IMO, the Ruger SP101 platform works great for many women. The frame size is small to medium and fits smaller hands. You can get a 357 Magnum and then shhot 38 Specials when you don't need the full magnum power, or, it now comes in 22 LR. You can get snub nose, 3", and now a 4.2" barrel. For the Ruger, I would avoid the chamberings that need moon clips, better to stay with the 357 Mag or 22 LR.
For Home and Target Use, This Ruger is Nice!