A dog may miss its mommy because of its instinct or its desire to gain attention or reward. Dogs are social animals who enjoy companionship and interaction, so they may look to their mom for connection and attention. This behavior is usually passive and may occur when the dog observes mom performing certain activities or being in the dog's presence. Dogs may also miss mommy because they want to receive rewards, such as food or games. Dogs may find that if they miss their mommy, she will give them good things to eat or play with, so the dogs may use this method to get what they want.
If the dog's missing mommy behavior starts to affect your life, you can try to change the dog through training and training Dog Behavior. You can contact a dog behavior trainer or get help through dog training books or online resources.