Two Smith and Wesson 659's. Each of these guns would likely survive the next 300 years or so. They can be found for about $300. Exceptional quality, solid stainless steel, large capacity 9mm's.
In a survival situation where I don't want others to know what I have on me, I'd much rather have a good solid handgun, and a good spare for my spouse, than a rifle. Two well trained partners with good handguns is hard to beat. Besides, what am I going to lug around and use a rifle for - shooting wild moose and white-tail deer, like the other 300,000,000 folks with AR's, long guns and shotguns will be doing in the first 10 days? No thanks, just give me two good solid 9mm handguns. I assure you that I can carry way more 9mm ammo than I can 12ga shot shells or even 5.56 ammo. And, at the ranges I'll be concerned about it will be plenty effective!