Maybe the truth is too hard for mummy to bear. For example, if you got into a big trouble at school like a serious fight, you might be afraid that mummy would be very disappointed or worried, so you choose not to tell her the true story.
I think it might be a very sensitive and personal story that could cause trouble or hurt if mummy knew. Maybe it involves family secrets or something that could upset her.
The movie 'Don't Tell a Soul' is purely fictional. It was crafted by the imagination of the writers and filmmakers, not based on real events or people.
The Mummy is not based on a true story. It's a product of creative storytelling in the realm of film, designed to thrill and captivate audiences with its fictional plot and characters.