If a member of the group displays signs of hypothermia warm them up by means available. Usually putting a warm body in a decent bag with a cold body will do the trick, especially with a shelter or tent available. Then walk out if the trail is passable and the distance/grade manageable. Keeping moving is rarely a mistake when within 5 miles of a vehicle. Exceptions include flooding, blizzard conditions, and steady cold rain in the absence of adequate gear. Huddling together in dry sleeping bags in a shelter or tent beats walking in conditions where exposed walking will not warm you up. Fire building skills in bad conditions are a good thing to teach/learn as well. A hiker with a blow torch should be able to start a sustainable fire in most conditions.