They are caught in a time loop.

The time loop was stopped when Tobin got out the moment before Becky and Call got in. Meaning, everything that had happened after that point won't happen. Becky, Cal, Travis are saved. The loop is broken... but only for them.

Unfortunately, the family got in before Becky arrives and so they are lost. Going on repeat forever; each time they die, a ”new” will arrive.

Notice how the boy keeps calling for help even that he is now out? It means (must mean) this version of him is still in the loop (together with his mom and dad) [messed up ending for this kid].

That then means Travis (the stone toucher) is still in the loop also. However, since Travis won't come ”later,” that Travis (the stone toucher) will be the last one. And as he dies, he is saved to never return.

But the family is doomed to roam forever. Or rather, I see no argument why they wouldn't?

Or... why do I think the family came first? If they didn't, they too will be saved from the loop once they (those alive in the grass when Becky hear the boy call for help) die.