What limitations are you placing on the size?
I was thinking about three. If you want to be totally simple, you could go with a small handgun in what ever caliber you want. I would go 9mm, since it will put a hurtin' on someone and ammo is cheap and available everywhere. A Makarov might be a good shoice as well. They are cheap, but known to be very reliable. Ammo is also cheap, but not as available as the 9mmx19. But that just means that you have to order 1000 rounds from somewhere and you would be set for quite some time.
Then, you need a 22LR of some sort for feeding yourself. I have already suggested the CZ 452, but that one is also your choice.
Third is a rifle. The particulars depend on your abilities, tastes, and your surroundings. For my uses, I would take a scoped 308. Good ammo is abundant and cheap (Port surplus). I live in a rural area where the ablility to really wing one out there could be useful. And I also would prefer to stay out or range of anyone who is shooting at me if I can. And, you can't waste ammo as easy with a bolt action. If you live in a built up area, then a semi-auto firing one of the intermediate rounds may be better. Or maybe a lever action 30-30. Given the money and space, I would prefer to have one long range rifle, and one with better firepower in case you need it.
I personally could go without a shot gun. They are loud, their range is limited, and the ammo is expensive compared to a 22LR and takes up alot of space. You get about 50 rounds of 12GA for $9. For the same amount, you get 500 rds of .22. Do the math: 500 squirrels, rabbits, etc. vs. 50. I would rather go with economy.
If I didn't have alot of money to spend, I would consider older military rifles like the Mosin-Nagant. Ammo is about $100 for 500 rounds of noncorrosive Wolf, and the rifles are cheap and tough.