My instructor taught me that, although the sound of a pump shotgun being stroked may make a burglar wet his pants, the sound of it being short stroked and jamming will bring a smile to his face. If she decides on a shotgun, she should keep a round in the chamber and not rely on sound effects. Another nugget passed to me was, the barrel of a shotgun preceding a homeowner into a room is a good grab point for an alert burglar. Two strikes against shotguns as far as I am concerned. If she is competant with her .38, have her get some +P ammo for it. In .38 cal I heartily recommend the S&W Model 10 or 64, Military and Police .38 with fat barrel. It has great balance, and great followup shot ability due to the barrel. Shotguns are good for intimidating people who are at a distance, but I don’t care for them in a dark house. My two cents.
OK, here's another nugget for you: clearing a building room to room is work for professionals, not homeowners.