We had the same problem. The dog that remained was an 11 yr old Shepherd. I would highly recommend not getting any other dog for the moment. Dogs grieve. Your chow needs at least several months for that. If you do eventually get a dog let her pick it out. Do not offer her puppies as an option - she will wear herself out trying to keep up with a child. You wouldn’t pick a child as a companion for your grandfather - same thing. You can help her grieve by explaining death to her. Over and over if need be. She’s not stupid, she’s a dog, and she will understand.
God bless and good luck.
How do you explain it?