Wendy says to David McClean that “They’ll be here directly” in paragraph 68 of "The Veldt." What can we guess happened to the parents?
To guess what happened to the parents, we need to go back a few lines, to the period before David McClean arrives. At that point, we learn the following about the parents, who are trapped in the nursery:
Mr. Hadley looked at his wife and they turned and looked back at the beasts edging slowly forward crouching, tails stiff. Mr. and Mrs. Hadley screamed. And suddenly they realized why those other screams had sounded familiar.
Right after this, the scene breaks, and we cut to David McClean saying, "Well here I am," while standing in the nursery door. The children are having a picnic lunch in the veldt. McClean asks them, "Where are your father and mother?" It's at this point that Wendy says, "They'll be here directly."
We can assume from what happened before Mr. McClean arrived that the lions killed the parents. This is reinforced by what David McClean sees: the lions feeding, then moving to the water hole, then the vultures descending. When Wendy makes her comment, we can imagine several scenarios unfolding: first, she might be lying and the parents will never arrive, because they are dead and eaten. Second, we can imagine that she might be indicating that the lions will emerge with the remains of the parents, though that seems unlikely. Or, she might be saying that her "father and mother" are, in fact, the lions, the creation of the viewscreen: "they'll be here directly ..." In that case, we can imagine that Mr. McClean will also be devoured. But whatever happens, our assumption must be that the parents are dead.