1) A lever-action .30-30. Ammo is readily-available, it has more than enough "knock-down" power for defending your property, and is the archetypical hunting rifle. If the supermarkets run out of meat, it's good to know I have plenty of deer in my neighborhood! Inexpensive options include the Mossberg 464 and the Rossi Rio Grande (made by BrazTech in Brazil), though there should be plenty of Winchester 94's readily-available on the "pre-owned" market. As an added bonus, chances are pretty good that this will not end up on an "Assault Rifle" Ban list.
2) Mossberg 500 12ga shotgun. Again-- great for home defense, with 00 buckshot, assuming the user can handle moderate recoil. It's inexpensive, and it just works! Being able to go to the local pond and bag a few ducks or geese is an added bonus. Remington 870 works just as well-- I prefer Mossberg's tang safety and better value. Both can also be had cheaply on the used market. Again, plenty of readily-available ammo.
3) This is because of the region I live in-- any used Mauser-action rifle in .338 Winchester Magnum, with iron sights, or an "over-and-under" setup. Why? Four words-- Bears and Mountain Lions!