Final answer:
The most appropriate form of address for Mrs. Genevieve Nesmith, age 81, is Mrs. Nesmith.
Step-by-step explanation:
The most appropriate form of address for Mrs. Genevieve Nesmith, age 81, is Mrs. Nesmith. The title 'Mrs.' is commonly used to address a married woman, while 'Ms.' is used when the marital status of a woman is unknown or irrelevant. 'Miss' is used for an unmarried woman, and 'Genevieve' would be too casual and not respectful enough for addressing an older woman.