Good choice, especially since it has a safety for both right-hand and left-hand shooters. I have the Mossberg along with an Ithaca M87 Police pump, a reliable gun but the righty cross-bolt safety is a bit of a pain for me as southpaw.
Shotgun extends out, easy for someone to grab. Self-defense experts recommend a revolver or semi-auto. I would recommend a S&W .357. Kick isn’t as heavy as a .44 or .45, and it will do the job. A revolver is ALWAYS ready to shoot, and you don’t have to work the slide or worry about it jamming.