I've read this interesting theory in a tumblr blog called littleahsthings.tumblr.com about Violet being dead and how would she help Tate if she was dead. Read what the blogger said:
1. She wouldn’t cross-over if she died in the house. That’s like a “house-rule” as I like to refer to it. She...
Sooo... About the the theory that Tate couldn't save Violet in time, and that now she is also dead...
Honestly, I really don't want to believe it (Violate fan here), but I think it can be true.
I guess we'll find that out on the seventh episode, but just think about it: the last moment we see...