As you mentioned, groups will have the advantage.
Food is definitely critical, but I believe that a preparedness-minded community is the way to go, rather than any "lone survivor" silliness.
If the community is isolated enough, takes proper precautions (particularly in remaining inconspicuous), maintains lots of food production and is well-armed, I believe that they would be the best chance of surviving.
Think about it. Let's take an EMP scenario. The cities would tear themselves apart swiftly. Within a couple of weeks hordes would be fleeing whilst killing each other. Obviously, they'll head for the country. Sounds like a death sentence for our prepping community, right? Wrong. That is a TON of ground to cover, and most modern people have zero sense of geography. To make it anywhere, they'd have to rely on roads.
If our community - let's say it's in the Appalachians of North Carolina, a region I'm relatively familiar with - is properly prepped, they'll be able to have EASY advance warning of the hordes, and the odds of the desperate masses finding them are slim to none.
One travelling individual may be less likely to be picked on, but he'll be easy prey for any gang of scavengers. A well-prepared community on the other hand stands a much better chance of long term survival.
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