Why does Mattie blame herself for Grandfathers death in the book Fever 1793?

In "Fever 1793," Mattie blames herself for her grandfather's death because she feels responsible for his well-being and believes that her actions contributed to his demise. After he falls ill while trying to protect her during the yellow fever outbreak, she struggles with guilt, thinking that if she had been more cautious or attentive, he might have survived. This sense of responsibility and her emotional turmoil highlight the intense pressure she feels in a crisis and her desire to protect her family.