Upon arriving, you'll automatically start another conversation. They should usually be found in a nearby location on the map. Go through a straightforward discussion with them and head towards the location of the family whose youth was killed. The young member does seem to lack a blue exclamation mark, unlike other quest targets, so double-check their name. You can highlight important NPCs using the ALT key as long as you're physically visiting the town or village with your character. The NPC from which you pick it up will direct you towards the young member of their family which is usually found in the same town. Although the wounded party was offered blood money, they're hellbent on shedding the blood of the killer instead. Mount & Blade II: Bannerlord's Family Feud quest revolves around a young member of one family killing another by accident.

Just talk to every NPC with a blue question mark in the town menu. Like its peers, the Family Feud quest pops up seemingly at random and can be picked up from NPCs in multiple towns and villages across Calradia.

Marriage mount and blade warband