I can't seem to find this movie I have been after for the past few months :(

Here is the plot of the movie from what I can remember;

In one scene, the son looks at a window from outside and sees an old man looking out of the house so he waves at him.

The woman in the house finds an old lady who used to live there, for answers.

The father digs up grave stones in the backyard on a rainy night.

The final "showdown" is in the garage or some kind of room like that. And there's a big face with some kind of portal/vortex underneath it and it's sucking in the kid.

Few people have said poltergeist, but its nowhere near that movie!

I could very well be

Are you the real slender man?