Easy
First you need to understand what my intrepretation of the SHTF is...
SHTF = Kaos to the point that extreme self-defensive actions are required. No calvary is on the way to save us, our life expectancy is in serious doubt, civil services are just about nonexistant, no food, water, or utilities are available, and things might remain in kaos for quite some time.
Choices?
Pistol = S&W or Colt mid-frame .357 Mag w/ 6" barrel
Rifle = .308 pump (Remington) w/ 2x7 wide angle scope
Reasons?
Both pistol and rifle need to be accurate, fully reliable, and easy to use. For defensive purposes I'll want to take out threats while they are still as distant as possible. Both weapons in the configurations described will do that.
Both weapons might also be needed for hunting (so I can feed myself and group when there's no other alternative but to hunt ). Both calibers are widely available in a variety of loads to cover everything from SD to small/large game hunting. (Although I'd really like someting a bit more robust than .308 if I need to take on a bear, I could if given the right load. Because of its combination of wide availability of military/hunting ammo, inherant accuracy, and easy of handling, it has to be .308).
Why a pump and revolver? They're simple, reliable, and if I'm taken out those remaining in my group will have no problem picking them up and figuring out how to use them. Ever seen anybody who didn't know (almost instinctively) how to use a revolver or pump? -- Maybe its in our DNA or something??
BTW, the question was rifle and handgun. Had it not been rifle, I would have selected a Remington 12Ga Shotgun (870 Wingmaster w/ mid length barrel).