Houses we recognize are usually about our issues from the time period we lived there or remember them from. So, it might help to look at what was happening with your mother during the time period of your life you most remember visiting with your granddad at his house.

I lived alone in an apartment from 1973-1986 and dreamed about that apartment from about mid-80's until 2003 or 2004. I lived there when I saw my T the first time, 1978-1987 and I saw my T again 1996-2005 so we kind of knew there were things we didn't clear up from the first time I saw her. My dreams from that period often were oppressively depressing or scary/upsetting.