People concern themselves with what others will think or feel about their personal struggles and life choices when truly no one cares or will ever go through your pain or Joy with you.
There is an adage that says, "what you won't eat, don't smell it". You already know your mother won't allow you marry a northerner not just someone from Bauchi but you led him on and now you're trying to ruin his life by still leading him on with your indecisiveness. Please if you know you can't win your mum's approval to marry this man then tell him and let him know before he'd break one girls heart for yours only to not even win it. Don't let him lose both ways, that will be very wicked of you. Say No and mean it, stop talking from both sides of the month. Imagine, roles are reversed and a man is treating you this way. How would you feel? Let this man go and find the man your mother would approve of in front.
Note that marriage is more than marrying someone that meets the approvals of family and friends, it's about you and the person you want to marry. Is he a good man? Does he love you? Does he love your people and accept them? Does he care for you and your family? Will he stand by you through good or bad times? That is what marriage is. God forbid you marry someone your mother wants and he doesn't make you happy? Be selfish about the things that make you happy