What does "wynd" mean?
I'm an American, I don't speak English! 
It's an old-fashioned spelling of "wind" as in "Blow blow though winter wynd.." a song from Shakespeare's play "As You Like It" but in parts of North Yorkshire, notably Richmond, a wynd is a narrow lane in a town running between two properties.
In other parts of Yorkshire, it would be called a snickleway (York), or a ginnel (West Riding). A more general name is an alley.
Edit: However, I imagine that Emma is really using it as the old-fashioned spelling of wind.