Good Morning and welcome to Just answer. I am Dr. Loretta, a licensed veterinarian and I am happy to answer your question.
It is clear that you have fleas in the area where you have the mother and puppies so they will re infect them even after baths. the best thing to do is to clean all the bedding and remove the puppies and mother from this area for 1 day and bomb the area with a good flea bomb that will kill not only the adults but also the larvae. These can be very stubborn and I am not surprised that you are still having problems. The fleas do not live on the puppies.....they jump on for a drink and then off...
use the bombs and disinfect all bedding by washing them.
Sincerely, XXXXX XXXXX