One centerfire rifle in a popular and effective caliber. Leave the specifics up the user.
One centerfire handgun. Once again in a popular and effective caliber with the specifics left up the user.
One shotun in either 12 or 20 gauge. Yadda, yadda yadda..
And one .22 rifle or pistol.
Careful selection of those four should cover 90% of your needs.
Heck, I'll even be more specific: The rifle should be .308, .30-'06, .270 or .223. The handgun should be .38/.357, 9mm, .45 ACP or .40 S&W. Those calibers are effective in multiple roles and are easy to find.