Friends grandmother's ghost story from India

This is my friends childhood story.., she says she feels her grandmother's presence in her childhood even after grandmother's death. Sometimes she feels like someone calls her name in grandmother's voice from back and when she turns around someone disappears like a black shadow . Sometimes in her dreams even in daylight she also faces same thing. She tried many time to tell her parents but they did not believe her as she was a child then . One day she clearly saw her grandmother in dinning room where she used to sit and eating nuts and she became unconscious . When she wakes up she found herself in her grandmother's bed. After repeated episodes she finally convinced her parents and they give her a chain from a priest to wear regularly and from that day she never see her grandmother again.