Home Defence.

[paperboy]

A 20 gauge may be better for her. Less recoil than a 12 and you still have a good choice of different loads for it. I personally prefer a 12 gauge but I am not recoil sensative. There are many good choices out there for pump shotguns. H&R, Mossberg 500, Remington 870. Don't overlook used ones either, the Winchester 1300 is an awesome shotgun.

 

[Hookeye]

FWIW I wouldn't buy a 12 if I already had a 20.
Currently have a 870 Supermag turkey model.
But wouldn't feel bad about a short little Special Field 20 gauge