Since we don't know the story, I can only assume. Maybe the scariest part was when Frank realized that the ghost seemed to know things about him that it shouldn't. For example, if it whispered his name in a creepy way or seemed to be following him everywhere he went in the story.
Well, without more information, it's hard to say exactly what Frank's childhood ghost story is. It could involve seeing a strange apparition in his bedroom at night. Perhaps it was a figure that would appear and disappear, leaving him feeling terrified. He might have tried to tell his parents, but they didn't believe him at first.
In a Frank Usher ghost story, a group of children were dared to spend the night in an abandoned Usher cottage. As the night fell, they started to feel a cold presence. One of the children saw a face at the window, a pale and sad face. They all huddled together in fear. The next morning, they ran out of the cottage, swearing they had encountered the ghost of someone related to the Frank Usher family, and they never went back there again.
There are no proven 'Anne Frank ghost stories'. Anne Frank's story is a tragic and real historical account of a young girl during the Holocaust. Her diary is a powerful testament to the horrors she endured, not a source for ghost tales. We should respect her memory and the significance of her story in the context of history and human rights.
Since I don't know his ghost stories specifically, it's hard to say exactly. But in general, an author's unique style in ghost stories might come from their use of setting. For example, if he sets his stories in very unusual or little - known places, it can make the stories stand out.