"Back in the day" the old timers around here couldn't afford much. Not many can "do everything" with a handgun, so let's eliminate those. We are left with rifles and shotguns. One of my great grandfathers had a model 94 saddle ring carbine in .30/30 but unlike many he had a Forehand and Wadsworth break top .32 revolver, "to take to the fair". He was also an "Ice Man" in town (the frozen water kind, LOL) and traveled with money. Another great grandfather had a model 94 saddle ring carbine in .25/35 but also had a side cocking single barrel 12 ga. I am blessed to have/had all of these guns in my possession. I gave the .32 break top to the grandson of my uncle as it was his grandfather that gave it to me but still have the others.
I'm only a year or 2 older than HWB13 and like him have had multiple guns since I was in my early teens. I'm glad I don't have to choose just one! The old timers would have a rifle they could hunt deer with or shoot woodchucks, and bears, foxes, coons, or skunks getting into the hen house.
Here is what I would consider the minimum number and types of guns to have-
Bolt action .308 or .30/06 rifle or carbine
12-gauge pump or double
.22lr semi-auto or magazine feed bolt action (must be accurate)
1911 .45acp handgun
We live in a different world than the old timers did. Most people today need to worry more about a meth head breaking in than a fox getting in the hen house.
I would not want to be without a handgun in today's world, but for "survival" I would have to agree with blue raven, an accurate repeating .22 rifle makes the most sense to me.