Arguments over mums maiden name in our baby boys name

Me and my OH are discussing baby names for our little boy he wants his mums sir name in the name and I really don’t want it in the name. She keeps mentioning how she wants us to put it in our baby’s name like we have no choice! I don’t want my baby to have two last names ! And her last name is so unusual and long I can barely even spell it ! Am I being selfish ? My OH has his fathers name in our first sons name and I have my granddads that passed away in his name. But I just think it’s weird to put his mums sir name in our new baby’s name, I wanted my dads name but we just can’t compromise. As I don’t want both. I feel like I’m being so selfish ? But I just really don’t like her last name