How Freely Do Ghosts Really Move About?

This is very strange. There is a house, a few blocks up and across the street from our house. It, too, is said to have been built by the Haine family and to be haunted. Well, this house is up for sale-- yet again. Our activity has slowed up some. However, my mother has claimed that she has seen the old woman, that used to hang by her neck from our ceiling fan, in the window of that house. Can ghosts and spirits move from house to house at will? They seem to come and go as they please. I do remember one recent Sunday morning where my mother and I were fall cleaning, upstairs, and we didn't seem to be disturbing anyone. Later, after my mother had come downstairs and I remained upstairs to finish up, she called up to me and said that she had just seen the mother, father, little girl and the cat come through the front door. The door didn't open-they came through it. It was as though they'd been out for a Sunday afternoon outing. Is this possible?

On a more recent note, about a week ago our dining room door opened up for no apparent reason. I wonder if a new spirit might have joined our family.
Just today, my mother was looking into the glass of our china cabinet. She saw the reflection of a man's face looking back at her. She screamed and it faded away. She isn't certain who's face she saw, except that she thinks it might have been the father ghost.