I basically don't believe in GHOST. But it doesn't mean that i don't believe in DEMON. I believe that good (GOD) and evil (DEMON) are both sides of a coin. If GOD is there, so is DEMON. But demon doesn't mean it should be a ghost or a spirit. Both God and demon are inside our heart. Its God who makes you do good, and its demon who makes you do the bad.
This whole, haunted and possessed thing is just something shown in the movies. And since this topic is very interesting one, people talk a lot about it and this in itself is publicity. After death there is nothing,no spirit no ghost,nothing. Death is THE END.
I'll just give you one example--- My family home is said to be possessed. The people around there says that they have seen my granny moving around the house even after her death, they even say that they smell my granny's purfume, they hear sounds from the house even if the house is empty. But if any of this was true, even i would have experienced this?. But i have never. not even my parents. So we understood that this whole episode was just a interesting talk between the people and the workers around there. Seeing ghost or experiencing it is just the ploy of our mind. Our mind is the most complex thing in this world.
When you sit alone, you already feel vulnerable, n so only when you think u hear someone talking, actually u can hear it. Its just your mind who is playing with you. And if you have a weak will power or mind, you actually start to think that is real. for instance, you only move the chair or on the fan, then u forget it, n you think that this was done by someone else whom you cannot see. This type of things has happened with me a lot many times. Once,i had kept milk on the gas stove for boiling,then i went to watch TV. In the mean time i forgot about the milk, but after 1 hour or something i remembered about the milk and went to the kitchen to off it,was surprised to see the burner off. At first i do feel scared,but then i thought n thought, then it crossed my mind,i had gone to the kitchen in between just to keep a cup,i had turn off the burner then. It just slipped my mind at first. Now you see, if my mind was week, i would be thinking that this is the work of a ghost, but instead i thought about it and got the answer.
I think your friend need to see a psychiatrist, you told that she always has to make sure that there is always two people in the house,cause it bothers them wen they are alone. when she was with her two kids, it same as to be alone cos they are kids. And now about the things moving, this can be because of the megnetic fields or the eletro magnatic force.