I know I'm not reading this right. In my view the haunting absolutely happens for the mom.
As far as movies go this is a pretty good one. I liked the way that after doing the typical horror movie stuff they cut to the part of dealing with the situation and establishing credibility for the Warrens. It gave me a chance to stop sh!tting my pants.
In terms of what's real and what's fake I'd like to be left alone in a room with a clairvoyant to ask them if they knew what was about to happen to them.