In very small towns, such as Maycomb, the "universe of obligation" is thought of in terms of being neighborly and helping one another, especially in crucial times.
In the Deep South, which is part of what is called "the Bible Belt," people would think of this universe of obligation as simply being Christian. Therefore, they would "do unto others" as they would wish done to them. [Luke 6:31]. In other words, Miss Maudie's neighbors help her because such actions are neighborly and right.
Another passage that the citizens of Maycomb follow in Chapter 8 is also from the Gospel of Luke:
And the crowds asked Jesus, “What then shall we do?” And He answered them, “Whoever has two tunics is to share with him who has none, and whoever has food is to do likewise.” [Luke 3:10-11]
Miss Maudie is certainly a person that the community feels is worthy of protection and help. Because she is an older woman who has no family living with her, she clearly needs assistance from others when her house catches on fire.
The old fire truck, killed by the cold, was being pushed from town by a crowd of men.
Unfortunately, when the men finally get the truck before the burning house, the hydrant water is so cold that it freezes in the hose, bursting the hose as chips of ice are sent "tinkling down onto the pavement." Apparently, all that can be done is to salvage Miss Maudie's furniture. Atticus carries out her heavy oak rocking chair, knowing this chair is what she values the most. Miss Maudie's boarder, Mr. Avery, throws his mattress from upstairs as well as some furniture. Soon, men shout to him that the stairs are going and he better get out; so, Mr. Avery barely squeezes himself through the window and tries to slide down a pillar, but he slips and falls into the shrubs. When the fire rages and threatens nearby houses, fortunately, the fire truck from a neighboring town arrives and pumps water onto the Finch roof and others.
With her house a total loss, Miss Maudie receives the charitable offer from Miss Stephanie that she can live with her "for the time being." Grateful, Miss Maudie expresses her concern that her burning house has caused so much commotion and danger.