Psychologically speaking, we should warn ourselves that the deceased (grandmother) does not accept the reality (wants to resurrect) and do more filial piety when approaching life.
Grandma's death is a fact, and you know that you can't help her, so in your dream, she should represent the old man you are close to in reality, that is, your subconscious is asking you to be better to your father, and it will be many years before he will be "at ease".