Walking dead?

[Monochrome Delirious]

My grandmother passed away on June 19th. Last night I dreamt that I was at her wake (which has already taken place) and I was sitting on a chair next to my father. In the dream, the room was literally a mirror image. The casket was at the far right end of the room. During the dream, my Grandmother got out of the casket and began walking towards the door. She looked like she did in the casket though, she didn't look alive and she walked almost like a zombie. My stepmother and my aunt (my aunt has passed on also, she is no longer with us) helped my Grandmother back to the casket to lie down, and the wake continued.

I don't even know where to begin to look to interpret this dream. Any ideas?