The meeting at the Finches’’ house in Chapter 24 is a meeting of Aunt Alexandra’s “missionary circle.” The point of the meeting is to learn more about the Mruna people who live in Africa.
The meeting is relevant to the book because it shows how hypocritical many of the women of the missionary circle (especially Mrs. Merriweather) are. They seem to be deeply affected by the plight of Africans in Africa. At the same time, though, they say horrible things about the African Americans there in Maycomb. They show no regard for the feelings and humanity of those African Americans that they are in daily contact with even as they seem so concerned with Africans in Africa.
Chapter 24 is all about the meeting of the Ladies Missionary Circle to discuss the course that Mrs. Merriweather is giving on the Mruna people of Africa. They discuss the missionary J. Grimes Everett's work and the poor people of the African jungle and their terrible conditions, according to Everett:
"The poverty...the darkness...the immorality" (Ch.24).
Mrs. Merriweather promised J. Grimes Everett that when she returned back home from her trip to his camp that she would teach a course on the Mrunas, and that is what the meeting in Ch. 24 is supposed to focus on.
Of course it goes in another direction entirely when the ladies of Maycomb begin talking about their hired help, all of whom are African-Americans. Their sympathy for the Africans in the jungle is not the same sentiment they have for their African-American servants, who they find to be ungrateful. Lee's point in this chapter, and of this meeting, is to show the hypocrisy of some of the good Christians of Maycomb.