IMHO, There are 4 types of firearms needed for self defense/survival

1. Pistol - for all around defense, and to use till you can get to your rifle/shotgun
2. Shotgun - for close range defense or hunting fowl
3. short range rifle - self explanatory, or you could just go with #3 or #4
4. Long Range Rifle - When you need to reach out. Defense/Hunting

and of course, plenty of practice and field ammunition for all. Reloading equipment and stockpile would be great too.