If I was limited, and thank the Good Lord I'm not, I would have to say a 12 ga shotgun, a 30-06 bolt action and a .22 rimfire would be my choice for a minimum arsenal. If I had to include a handgun into this it would be a revolver in .357 with a 4 or 6" barrel.
My picks are solely based on versitility. There are better choices for different areas, but for all north america, these would be my picks.