How long has it been since the other dogs passing? Consider getting another dog for it to play with? I had the same thing happen to me i had to put my one dog to sleep because she was to old and had cancer and my male dog was really upset i just gave him lots of attention and spoiled him rotten it took some time but he got through it.
We are going thru the same thing. Mandy and Tina are really having a hard time with Max's passing. It has been over a month now and Tina goes under the bed and stays or sometimes she wants in the closet. I just love them and try not to mention his name around them and play alot with them. My vet said it will take time because they are mourning. Tina also tee teed in the house a couple of times and that is something her or Mandy has never done. Sad, to see them go thru and I am sure they feel what we feel. They have seen me cry and cry and they know something is wrong. Just takes time is all I could possibly tell you. We are taking it a day at a time.
Dogs take a lot of their emotional cues from us. I think when you notice that the humans in your brood start to move on, your dog will too. It's a process for them just as much as it is for us. I agree, just love her(?) up real good. Let her know she is not alone in this. She'll come out of it. It may take a few months for her to adjust without her mom there. Animals don't feel a long-term familial bond like we do. But she was her buddy. And that's gotta suck!
We have a litter of puppies right now who are 7 weeks old- they will be leaving in a week. We have all of them sold but one. I am not sure how she will be after that and even the mother of these puppies will be. There have been so many changes all at once here.