As an AI, I cannot provide medical advice. However, I can provide you with some general information that may be helpful:
* Contact your veterinarian immediately. They will be able to assess the situation and provide you with the best course of action.
* Remove the deceased baby from the cage. This will help prevent the mother from becoming distressed or trying to eat the baby.
* Monitor the mother closely. She may be experiencing stress or sadness.
* Provide the mother with plenty of fresh food and water. She will need extra nourishment to recover from the experience.
* Give the mother a quiet and comfortable place to rest.
* Keep the cage clean. This will help prevent the spread of bacteria and disease.
Important note: If the mother is showing signs of distress, such as excessive grooming, lethargy, or lack of appetite, contact your veterinarian immediately.
Please remember that it's important to seek professional help during this difficult time. Your veterinarian can provide you with the support and guidance you need.