Oooh, it is really hard to have two puppies to train...I have been there...it is a real challenge!
I understand your mother's frustration, but it is something that the whole family should be involved in, the training. Otherwise, it will be tough to get a handle on.
What happens when the pups make messes? Are they punished? Do the pups hide to poop or do it right in front of you?
Sometimes it just takes longer for some dogs than others...and it depends on how they were raised at their breeder's home too.
Most breeders don't have the time to potty train their puppies, yet they do try to teach the puppies that there are certain places to go.
Crate training is important. Your pups should be in a crate if you can't watch them carefully. When they are out, you should have them tethered to you (you will need someone to help you by tethering the other pup to them because you can't do it with both.)
This link might have some helpful advice...at the bottom it has a link to houstraining too.
http://www.inch.com/~dogs/cratetraining.html