Final answer:
An-Mei's grandmother's statement that her mother is a ghost symbolizes the abandonment and absence of An-Mei's mother from her life.
Step-by-step explanation:
In Amy Tan's novel The Joy Luck Club, An-Mei's grandmother tells her that her mother is a ghost as a metaphorical way of saying that her mother is dead to her. The grandmother means that An-Mei's mother has abandoned her and no longer has any presence in her life. This reflects the strained relationship between An-Mei and her mother, as well as the theme of abandonment in the novel.