If you can handle it a 12 gage shotgun with 00 buckshot.
No need for buck shot IN the house.
That’s my suggestion. she can practice with target loads. If she were a big woman, I’d suggest throwing away that pea shooter and getting a .45.
00 buckshot is a macho suggestion and in a home defense weapon is a disaster waiting to happen to the homeowner, not the perp. In a house clearing operation, a load of #6 or #7 1/2 and will cut a man in half at 15 feet. The chances of this devastating shot penetrating a wall and injuring or killing a neighbor or loved one is minimized. Also, for a slightly built female with minimal self defense skills and for accessibility and ease of use and lethality, a Taurus Judge loaded with .410 defensive ball shot is a good suggestion.