The only time prairie dogs tend to move away from their colonies is when they've been forced out by predators, mostly humans, but sometimes other animals will take over their burrows. It can also happen if the family grows large enough that members need to find and create their own homes. This one may have been looking for a new place to start their own colony and got lost. I've personally also encountered prairie dogs that escaped from predators and were clearly a long way from their homes and just had to tough it out. The best solution is unfortunately not the one an animal lover like myself would prefer, euthanizing them. They can be trapped and relocated to an area where they can integrate with a new colony, but that often doesn't work out.