We can conclude that the grandson is dead because he is completely absent from the story, because of the grandmother's certainty that the medicine will not help him and because he has swallowed a very toxic substance.
This grandmother's certainty may be the main evidence that the boy died, but one of the themes of the story is the resilience and strength of black people in overcoming deadly challenges which give the reader hope that the boy is alive.
More information on themes at the link:
https://brainly.com/question/4008478