explanation ?

I think you are wondering exactly what everyone else is wondering. It was all right until a little over halfway and then it's just sort of like you entered another movie. I'm clueless to what was really going on here. :P

The old man who hired the company to kill him had years before been part of or the leader of a death cult. During the mass suicide though he did not die, therefore the souls of those that did remained in the house\grounds awaiting his death so they could enact their revenge. Edgar as a boy found him and took care of him till the time came for the old man to die. But he had to die in a specific ritualistic fashion or else the spirits would take him.

Mal was the perfect candidate to do the ritualistic killing as she was open to the influence of spirits, while Liv was to be the final sacrifice to appease the dead.

Now Mal is the caretaker\owner of the house and the question I have is who the young man is that apparently lives in the house too. I assumed he was a ghost but now am not sure. And her cat finding her? Probably an illusion (remember Edgar said "Keep seeing the house through your eyes.") or maybe it is now her "familiar" of she is possessed by the dark energy of the house.

So yeah some questions (like how much did the boss of the company know before sending the women out there), but I hope I have cleared up some of the story for you.