Answer:
Based on the given options, the words "withering" and "forgotten" in the poem seem to impact the meaning by describing the appearance of neglect and emphasizing the grandmother's condition. These words convey a sense of deterioration and abandonment, highlighting the elderly woman's physical and emotional state. They suggest that the grandmother has been left behind and ignored, which is further reinforced by the description of her surroundings. Therefore, the answer is "They describe the appearance of neglect and emphasize the grandmother's condition."