I'm not entirely sure which specific 'Hannah Grace' you are referring to. There could be many people named Hannah Grace. It could be about a particular individual's life journey, her achievements, or perhaps a story that has been made public about a Hannah Grace in a specific community or event.
There is no conclusive evidence to prove that the Hannah Grace exorcism is a real story. Many so - called exorcism stories often turn out to be a mix of superstition, psychological factors, and sometimes even hoaxes. Without proper verification from reliable sources, it's hard to take it as a real event.
The evidence that 'Haunting of Hannah Grace' is a real story might be somewhat scarce. It could be that the general concept of a morgue being a place of the unknown and the idea of something sinister attached to a body there is what they considered as real - life inspiration. There might have been accounts of morgue workers feeling uneasy or experiencing strange phenomena, which the movie took and dramatized. But it's hard to say for sure as the movie industry often blurs the line between fact and fiction for the sake of creating an engaging horror narrative.
One of the main events was Hannah's sudden change in behavior. She started acting erratically. Another event was strange noises being heard in the house she was in. And things like furniture being moved without any logical explanation.
One key element of the real story might be the morgue setting. It's a place where the story originated, which is often associated with death and the unknown. Another could be the unexplained events that morgue workers might have faced, which led to the concept of Hannah Grace being possessed in the movie.