What cause the grandma to die in the movie dantes peak?

In the movie "Dante's Peak," the grandmother dies due to a combination of volcanic activity and her own health issues. As the town faces an imminent volcanic eruption, she is exposed to hazardous gases and toxic conditions. Her existing health problems, including her age and a previous heart condition, contribute to her demise during the chaos caused by the eruption. Ultimately, her death serves as a poignant moment that underscores the film's themes of loss and the dangers of nature.