Answer: They want to help the missionary, J. Everett Grimes, who is in Africa working with this tribe. The blacks are a poor people in need of help as long as they are in Africa and not next door. Harper Lee puts this scene in the story to show the hypocrisy of these women.
They called it a "summer colony" which isn't commonly said... But they wore bathing dresses too which is something that women did years ago, so if not C then A.
