I know this isn't the right forum for it, but if you want a cheap and effective home defense gun for inexperienced shooters, my choice is a Kel-tec Sub2000 in 9mm. Before anyone starts laughing, there are a few models they make that don't have serious reliability issues, and this is one of them. I've got a S-12 for my side of the bed, but on the other side is a Sub2k with a 33rd mag of DPX and an Aimpoint.
Long guns are nearly always better for new shooters, the sight radius and extra stability from the shoulder make up for a lot of weak wrists and poor alignment. 9mm out of a 16" barre