Silko, the author said, “I wrote this novel to save my life.” How is Ceremony a novel of salvation, for Tayo, for its author, and for its readers? What are the limits to the salvation that it appears to offer?

I really don't know enough about the author to answer this. For Tayo, the ceremony was needed for him to come to terms with his ptsd. He needed to get in touch with his culture to begin healing again. The limits of salvation are that other people around Tayo who wish to do him harm are not really affected by it.