The mongoose and the farmer's wife

Once upon a time there lived a farmer and his wife. They had a new born son. The farmer's wife wanted to have a pet animal to protect the child which would also be a companion to the child. They debated and decided upon a mongoose. So they brought a mongoose and started rearing it.
A couple of months later, one day the farmer and his wife wanted to go out of the house leaving the child at home. The farmer thought that the mongoose would take care of the child while they were away. So they left the mongoose and the child at home and went out.
The farmer's wife returned earlier and on returning home found that the mouth of the mongoose was stained with blood and she immediately inferred that the mongoose had killed the child. In anger she threw a box on the mongoose and the mongoose was hurt badly. She then rushed inside to see what happened to the child. She was surprised to find a dead snake lying in the room. She could infer that that the mongoose had saved the child's life by killing the snake. Realising the mistake she went out of the room only to find the mongoose dead on the floor. She cried out load at her hasty action.