Translation:The grandmother says that you are never going to return.
So you think because you call your Grandmother "granny" the definition of abuela should change. I may call my wife "my main squeeze" but I don't think that the entire dictionary should change esposa.. BTW "I_ am_ banana: I follow your posts and you have taught me a bunch. I love the fact that we can help each other learn. That's what sets DL apart from the rest
According to my handy-dandy Spanish grammar, there are two ways to negate the verb using "nunca". One is by placing a "no" before the verb, with "nunca" at the end of the clause: "no vas a regresar nunca."
The other just puts "nunca" before the verb: "nunca vas a regresar." Other words that act this way are: nadie (no one), nada (nothing) ninguno (none), and jamás (never).
I'm going to guess that the two-negatives version is for emphasis, as scottann says.
No, calling an old lady "abuela" if she is not your grandmother can actually be offensive. When you say "La abuela" in most cases you refer to your own grandmother unless it's stated otherwise as in "La abuela de Pedro dice..." and no, there is no reason for "regresar" instead of "volver", they are completely interchangeable here.
Are grandmothers treated (grammatically) like body parts? It's hard to imagine that "The grandmother..." faithfully conveys the sense of the Spanish; should it be "your grandmother says..." drawing the possessive from the "vas"? It is hardly polite to refer to the elderly lady who has expressed her fears as "the grandmother" , still less "the old gimmer" as they might here in Norfolk (UK).