Final answer:
The narrator's tone in the excerpt from 'A Journal of the Plague Year' is best described as horrified, due to the shocking and terrifying depiction of the events.
Step-by-step explanation:
The word that best describes the narrator's tone in the excerpt from A Journal of the Plague Year is horrified. The description of shrieks and deaths conveys a deep sense of shock and terror, rather than bitterness, disgust, or indignation. The narrator's depiction of the emotional anguish witnessed in the streets during the plague year emotionally impacts the reader, suggesting that the most fitting word is indeed horrified, which reflects the extreme fear, shock, and aversion that are portrayed.