
Each breed, and individual mums are probably different, but our mums are off their litters by around 5 weeks, or at least 6 weeks when weaning onto solids is complete. I didn't think it fair to have her in there with them trying to nurse still, and hurting her. I look on weaning as not only meaning transferring from mum's food onto solids. And I liked to have the time between mum being off the puppies and the time they went home, so I was sure each puppy was ready for the outside world.
But again each litter and mums were individuals. Basset mums don't do much correcting - I did that !! and couldn't see leaving mum in with them to cope with their demands. She did her job from start to around 5 - 6 weeks, and then that was finished.
Just to add it helps the new owners with their new puppy if the puppy isn't missing mum as well as their siblings and surroundings. So by 7 + weeks for me it would be beyond time to have mum off the litter, day and certainly night.