Shotgun with the caveat your wife, in fact everyone will need practise to become accustomed to the recoil. Forget 00 buckshot. The next pellet sizes down provide greater projectile # and chances of hits. Your limitations on ammunition should guide you to buy some shot usefull on snakes and the big stuff for feral dogs and feral people. For a handgun get the 38 or 32 REVOLVER.Anyone can master the 38 and lesser calibers. The famed pistol master, Ed McGivern stated it was the most powerfull cartridge that could be used for rapid fire under full control. The .32 is something of a ne plus extra for outstanding accuracy and little recoil.Again, your wife will probably be able to shoot it well under stress. Semi automatic firearms involve safeties and various loaded conditions.In a high stress situation a double action revolver is very simple, just pick it up and squeeze the trigger.