The Mrunras are African people, and they are discussed to demonstrate the hypocrisy of the people who care about poverty thousands of miles away, but not in their own town.
The missionary circle meets in Scout’s house, with Aunt Alexandra hosting. It does not take Scout long to see how hypocritical these ladies are. They care little to nothing about the people who suffer in their own town, and pretend to care about Africans halfway around the world.
I heard Mrs. Grace Merriweather giving a report in the livingroom on the squalid lives of the Mrunas, it sounded like to me. (ch 24)
The Africans are balck, just like the Robinsons. Yet the ladies of the missionary circle have sympathy for the Mrunas, or at least pretend to, and almost none for the Robisons or the other blacks they treat so badly.