Take your dad to a gun store and let him handle a variety of types and models. Then try to arrange a test firing of the one(s) he likes best. He is the only one that pick the best weapon for him.
A .357 fired in a home at night will do wonders to your hearing and may well give you temporary night blindness.
Has has been mentioned, a .22 that hit's the target does more good than any caliber that misses. Also, a .22 will not deafen you or blind you with a muzzle flash.