I saw this on TV in the late 70s early 80s, it had a vacationing family mom, dad, grandma, brother and sister in a station wagon with a camp trailer. They break down somewhere and come under attack by some primitive caveman like dudes. Somehow grandma dies, they prop her body up in a lawn chair as bait, with a rope looped on the ground connected to the wheel of the station wagon. The caveman steps in the loop they pull him with the spinning wheel, run out of gas. Then they flee to the camper rigging the door with matches turn on the gas stove escape through the window. Caveman blows up when opening door lighting propane with matches. THE END
Help remembering the show/movie will be greatly appreciated.