For parameters to me the "walk" portion means you are limited to 1 long gun and 1 pistol.
Long gun- My immediate thought was between a .22 rifle and a 12 gauge shotgun. After a few minute's of consideration the shotgun won hands down. A 12 gauge shotgun with a variety of shells can take anything from little squirrels to (obviously at fairly close range) the biggest bears. I'm not worried about taking tiny game (let alone a right fight with people) past 40-50 meters so I'd rather have the versatility of the shotgun. Also since this is a limited time scenario (vs batman in the boondocks) the weight of shotgun ammo is not a huge issue.
A pump shotgun is ample for self defense against animals and people in anything but a crazy SHTF situation.
I would take a Remington 870 with a 28" barrel and a mix of shotgun shells all the way from #6 shot to slugs. Another pump shotgun like a Mossberg would be fine also.
Pistol- If I was gaming the scenario for the ultimate wilderness survival handgun it would be a .22 of some sort. This would be to save shotgun ammo by taking closer, easier shots on smaller game with the pistol. A .22 mag revolver of some sort would probably be ideal, given that ammo is limited to what I'm carrying anyway might as well have the extra power over the more common .22lr.
That being said realistically if I was getting stuck in an accident or whatever I would be carrying a centerfire pistol for defensive purposes, probably a .357 mag revolver so that is what I would have on my waist by default. If I move to Alaska I'll buy a .44 magnum revolver so I would be carrying that.
What are your ideal wilderness walkout guns? Do you actually take them to the woods with you?