I voted for the mothers last name. My biological parents weren't married, heck, they never even last through the pregnancy, and I received her maiden name. That's not why I voted for her name though. I voted fem because I believe that there should be more reasons behind the name chosen, I see nothing wrong with giving the baby her name, and I don't think he/she should have the fathers name solely because "that's the way it's always been.".

In any case, good luck and vibes to Ash and ze baby!