So, the two kids we were supposed to be watching were perfectly nice. The girl was about eight, the boy a couple of years younger. Mostly they just sat on the couch and watched TV while we were waiting for bedtime.
The problem was the house.
Well, the house and the ghosts. If you turned on the lights - or maybe particular combinations of the lights - you could see them. They were these figures outside the windows, screaming and pounding on the glass, but completely silent. And if you got enough of the lights in right combination of which ones were on and which ones were off, the rooms changed: different paint, different furniture, different hangings. Something about getting the lights arranged brought the house (or sections of it) closer to how it was when whatever created all these ghosts first happened.
We finally got enough of them right that the living room changed. Suddenly, the children we were supposed to be watching were gone, and there was another pair (another sister and brother) there instead... only these were ghosts. Kind of nasty ones, too. And once again, the only way to get rid of them was to complete the process and then deal with them somehow: as they had been? As they wanted to be? By preventing whatever had happened? Something. I'm not sure. I wasn't sure in the dream, either; I remember worrying that solving the puzzle might be going to trap me somehow, or make me vulnerable to the ghosts, I just didn't see any real choice.
So I finished arranging the lights, and the two child-ghosts went away. The other ghosts all melted together and flowed into the house as this sort of creeping black shadow, but I was somehow able to absorb them or consume them.
There was some other stuff later - the two kid-ghosts showed back up, and had to be settled into moving on - but that was after I'd woken up once, and it was much more disconnected.