At about midnight my father was in the middle of a heart attack. While we were keeping him calm and waiting for the ambulance to arrive I was looking out the bedroom window and in the reflection of the window and the mirror near the bed I could see my grandmother (my fathers mother who died 4 years earlier in that house) standing by my Dad's bed holding his hand.
He then told us he was feeling better and the pain in his chest was going. Ambulance arrived 3 minutes after that and he was fine.
In the same house my wife who had never seen a pic of my grandmother woke up one night and said she saw an old lady standing at the foot of our bed smiling. The next day I showed her a photo of my grandmother and she went white and said that was who she saw.