First of all, I don't care why you don't like grandma, but I want to say that it is your responsibility and obligation. At least this old man gave birth to your father and a husband to your mother. With this, even if she is just a neighbor, your family should treat the elderly well and let them enjoy their old age with your gratitude, otherwise it is useless for you to be admitted to graduate school.
Young people with higher education will grow old, too. If you put yourself in others' shoes. I'm worried about your grandmother's future.