* To protect her child. The mother may be trying to protect her child from the harsh realities of the world by calling the story a fairy tale. By presenting it as a work of fiction, she can help her child to avoid feeling scared or traumatized by the events in the story.
* To teach her child a lesson. The mother may also be using the story to teach her child a lesson. By showing her child the consequences of violence and cruelty, she can help her child to understand the importance of making good choices.
* To give her child hope. The mother may also be calling the story a fairy tale to give her child hope. By showing her child that even in the darkest of times, there is always hope for a happy ending, she can help her child to stay positive and optimistic.
Ultimately, the mother's reasons for calling the story a fairy tale are her own. However, it is clear that she does so with her child's best interests in mind.