In To Kill a Mockingbird, who is Sunday's offering being taken up for and why?

In Chapter 12, Calpurnia takes Jem and Scout to First Purchase African M.E. Church. At the end of the sermon, Reverend Sykes takes up a collection. After the congregation has given their tithe, Reverend Sykes counts the money and says that there is not enough. Reverend Sykes says that they need at least ten dollars to support Helen Robinson and her children while Tom is on trial. Since Tom cannot work, and Helen has to stay home with the children, the family has no income. Reverend Sykes tells Alec to shut the doors and won't allow anyone to leave until they have collected ten dollars. Reverend Sykes urges everyone to give another dime and even calls out a member of the congregation who did not give money towards the collection. Eventually, the congregation raises ten dollars for Helen Robinson and her children. Scout and Jem gain perspective into how the African American community supports each other.