The narrator mentions the remarks of the surgeon and the nurse (lines 36-41) primarily to B show that those present want to lessen the fear of Oliver's mother.
In this part of the passage, both the surgeon and the nurse make comments that aim to comfort Oliver's mother, indicating that they are trying to provide reassurance in a troubling situation. While their comments may seem somewhat misguided or lack empathy given the severity of the situation, their intent is to alleviate her distress.