I'm a bit late to the party but I just binged all of season 8 in about a week.
I think Reddington is actually going to turn out to be the actual Reddington. I don't think he will end up being her mother. Remember, he did the nasty with Anne a few episodes ago. I'm not a woman but, if I was and I laid down with a man only to find out he didn't have anything down there, I'd probably be pretty damn upset and would probably have thrown him out.