Mother cat starts hissing and growling at the sight of kitten

My cat had kittens Jan 26th and we have one that's still left here, her owner has already paid me, I'm just waiting on her to get into her new place so she can take her, anywaysss. My cat got outside the other day when my bf was letting the dog in and she was out there for about 2 days. When she came back she seemed all happy and I took her to find her kitten. When she seen her kitten she immediately started grooming her and licking her face, but I'm guessing from her coming in fresh from outside, she had some new smells on her and the kitten got scared and hissed with her back sticking straight up, which confused her mother and she did not like that. Started growling and hissing back at her.
So I took them down to the room where the box they were born in is, along with their food and litter to hopefully bring back some memories for them so they weren't all freaked out by eachother( should've took them in there to begin with, I was just exciting she was home). When we got in the room, it wasn't long before the kitten knew who she was and wanted to go say hi, but her mother wanted nothing to do with her. The kitten will be playing around with something on the floor, and she'll just be sitting up on her scratch post growling at her.
Does anyone have any ideas on what I can do to possibly get them to get along until she gets picked up?

I suspect the natural time of rejecting has come... With only one kitten left, they usually accept it. It may be worse with a whole bunch of them...

Did you spayed the mom? If not, I suspect she was in silent heat, and sneaked out to find herself a tom.
Found one such smelly one, and after the mating was done, returned home.

Which in part contributes to the process of rejection.

Let them have tow different litters, food and water places, so they dont need to go on each other temper, and can coexist in peace. Perhaps the friendship may build up again.

And please, go to the vet NOW, before the foetus is more than just a little clump of cells.


Good luck!