Why the .22?
The .22 rifle doesn't have a role in home defense, but in the context of prepper and surviving it definitely has a role. It's one of, if not the most popular gun and round. Ammo will be plentiful and is cheap to accumulate. Very useful for varmint killing and hunting. The ammo could also be used for barter.
Building a suppressor for a .22lr is easy and head shots are leathal. Throat shots and bladder shots will stop someone. Ammo is easy to carry in large quantities. Hand gun and rifle ammo.