I knew it was you, it's always you...

I think so. But maybe your timing is off. As you put it, it means she knew well in advance that he would come to save her.

I would take it to mean that while he was digging her up, she could hear and feel the activity, but could not see who it was. "I knew that the person who was in the process of rescuing me was you."

AvangiI would take it to mean that while he was digging her up, she could hear and feel the activity, but could not see who it was. "I knew that the person who was in the process of rescuing me was you."

Yeah but she was unconscious when he pulled the coffin out.
When he openned it he brought her round.

I just thought of another interpretation.
I know you'd come, you always do!

It's just the tense that bothers me. "I knew it was you"

She's speaking this to him in the present tense, but referring to the past tense. So there must have been that brief moment between when she first became conscious that someone was there, and when she was able to recognize him.

AvangiI knew it was you

I know in reported speech, if the event in question is still true, the verb could remain unchanged

eg The spokesman said the government is going...
But how about this?:

situation:

John finds Peter in the music room, and John says:

-I knew you are/were here./I didn't know you are/were here.