But his explanation of the nightmare is ambiguous.
In short, nightmares are similar to a warning and a protection.
Your grandfather's health is worrying,
And you must be afraid that your grandfather will suddenly leave without saying goodbye. Dreams tell you subconscious fears, and dreams hope you can pay attention to grandpa's health.
Chrysanthemums are white and sometimes pale. That is your impression of the hospital. In this dream environment, chrysanthemum can be understood as a hospital or a doctor.
In your dream of grandpa's death the next day, it means that you are already worried about your first dream, and subconsciously remind you to care about grandpa. After all, the dream doesn't want you to suffer the pain of losing your loved ones in reality.