As you pointed out, what they needed most was to stay home. Sounds like they really could have used a topo map and compass as well. Once lost and hunkered down, they needed fire (PSK) for staying warm, drying out clothes, being more visible to rescuers. Using some aluminum foil (PSK) to melt snow over the fire, they would have abundant water, a luxury in the desert. A whistle (PSK) might have made the searcher's job easier.