Forgot -- for the rifle, I'd suggest the AR platform. Not only are there tons of choices, ammo is readily available and I believe they are the MOST customizable defensive rifle platform available. I have one Colt H-BAR (currently wearing a DPMS upper) and one DPMS carbine. They have all been extremely reliable and surprisingly accurate. While you may not be looking for a hunting rifle, in a prolonged SHTF scenario, hunting may become a necessity. The 223 round is excellent for head shots on small game and with bullet weights available ranging from 40 grains to 80+ grains, I have no doubt that it would be capable of deer sized game with proper shot placement (though it would not be my choice for a strictly hunting rifle). Currently, high cap magazines are readily available and not overly expensive. A plus in preparing for a worst case scenario. My personal choices for SHTF weapons in order of importance is:
Shotgun -- with varying ammunition, can do everything except extreme long range. Only real disadvantage is size and weight of ammunition limits number of rounds you can carry at any one time.
Handguns -- semi auto primary, revolver back-up -- close quarters defense
Semi Auto Hi-Cap rifle in rifle caliber -- defense (both close range and long range), hunting
Semi Auto rifle in pistol caliber -- to match caliber of handgun. More precise aiming for greater distance than pistol alone plus shared ammunition with handgun.
Bolt Action rifle in large caliber -- big game hunting and extreme long range defense.