How does gram die in walk two moons?

Gram was bitten by a venomous snake. She did not receive full treatment, as she refused to stay at the hospital. Throughout the trip, it was obviously wearing her down. Her breathing became more ragged. She became more weak and tired. Her color started to turn gray. They took her to the next hospital, and they said she had a stroke. Gramps stayed with her through the night, and she passed away at 3 am.