Will Mom cat go find kitten?
Mom cat does not like the current nest, for whatever reason. She will move her kittens to a new nest. If you put the kittens back in the old nest, she’ll just keep moving them. Let her move them, otherwise she might end up killing them if she doesn’t feel that they’re secure in the place that you have chosen.
My cat used to do that to her kittens, she put one in the washer and one behind it, she might bring it back, or she might take the others over to it. You should try finding it before he/she does die. The mother cat normally moves her kittens because she thinks there not safe or she is feeling “claustrophobic” so look for the kitten and try leaving the mother and kittens into a “Better” in closed room.