Ok, I have two questions though.
1) What would happen if Nell's sister and her family found out that Nell had died?
2) What would Mr. and Mrs. Dudley think about the state of the house? Did they know that it was haunted?
"Did you think that I would harm her?"-The Phantom
[Major spoilers about novel and both movie versions.]
We've had a couple of discussions (at least) on this board about the ridiculous ending of the '99 movie and the loose ends left behind.
My opinion of how things may have turned out after the credits rolled:
1. The Dudleys seemed to know that the house was haunted in all three versions. However, in the '99 movie, unlike the earlier versions, the professor presents them with major property damage at the end.
I don't see how he could avoid legal problems, like a lawsuit or criminal charges. Would Dudley have said, "Oh, don't worry about replacing 300 windows; we know the ghosts did it."? I don't think so!
2. Nell's demise results in a similar problem. In the earlier versions, she drives her car into a tree. Awkward to explain, but not as awkward as the 1999 events. Homicide detectives would have even less reason to accept ghostly intervention than Dudley did. And Luke's corpse was in there too.
I suspect Dr. Marrow and Theo were arrested on the spot.