Shotgun, pistol, ammo for both.

I'm in an unfamiliar urban area, with at least a 15 mile hike between me and wooded areas/parks?

Not so sure I'd leave the relative safety of the vehicle gridlock to be out on foot where I don't know my surroundings.

And there's volcanic ash everywhere -- so eventually the vehicle will probably stop running anyway. But walking around in it for hours upon hours (lets hope there's a couple masks in the bug out kit) isn't great, either. Not to mention the possibility of getting lost.

Plus, a convoy of stopped minivans on the Interstate is likely to attract potential rescuers and attention long before two people hiking through the woods.

Either way you're in a bad spot. I'm not so sure I'd leave the house to begin with. It would depend on how bad the ash situation was. Are we talking a nearby volcanic eruption or just an ash cloud blowing in from elsewhere?

Good scenario! One that could definitely happen here in the NW.