On this page of the Assassin's Creed Valhalla guide, you will find a detailed walkthrough for Mother side quest.
Rewards: 1,200 XP.
In the place marked on the image above, you will come across a small hut from which a female-like voice will be coming from.
There is a pack of wolves roaming in front of the building - deal with them.
The entrance to the hut is barricaded from the inside, so you have to find another way to get inside. There are flowers on the roof of the building or the nearby grave - pick them up.
Walk up to the door - the lock will be removed. Inside, you will meet a man who mimicked a woman's voice earlier to encourage you to visit. After a short conversation, the mission will end.