In this chapter, Miss Maudie is meeting with her missionary circle women when Atticus comes in to tell Calpurnia that Tom Robinson has been killed in prison.
Aunt Alexandra tells Miss Maudie that Atticus is tearing himself apart, ruining his health, trying to get justice for black people in Maycomb. Miss Maudie replies that they are paying him the highest tribute possible. They (the people of Maycomb who do want blacks treated fairly) are doing this by trusting him to do the right thing. They expect Atticus to act fairly and they do not really think much of it because he is such a good guy that it is just normal for him to do right.
So the people of the town don't really pay attention to the toll the work takes on Atticus -- they are so used to his goodness that they take it for granted. That is the highest possible tribute.
If the reader goes to the text, he/she will see that prior to the dialogue between Aunt Alexandra and Miss Maudie in which Miss Maudie makes the statement quoted in the question, there are some of the members of the Missionary Society who speak in a deprecatory manner about the people who think that Tom Robinson should have been found not guilty:Mrs. Merriweather tells Gertrude Farrow,
'I tell you there are some good but missguided people in this town....Folks in this town who think they're doing right, I mean. ow far be it from me to say who, but some of 'em in this town thought they were doing the right thing a while back, but all they did was stir 'em up.
When Miss Maudie hears Mrs. Merriweather's insinuations against Atticus in his own home, and her insults about her "sulky" cook, Sophy, she is incensed. She says, "His [Mr. Merriweather] food doesn't stick going down, does it?" To this, Mrs. Merriweather replies, "Maudie I'm sure I don't know what you mean," and Miss Maudie counters with, "I'm sure you do."
After this tense moment, Aunt Alexandra swiftly passes refreshments (which she has let Calpurnia make this time!) and gives Miss Maudie a look of "pure gratitude" for defending Atticus's conduct of late. Then, shortly after this episode, Atticus enters and informs Aunt Alexander that Tom Robinson has been shot trying to escape:
'I guess Tom was tired of white men's chances and preferred to take his own.'
Upon hearing this tragic news, Aunt Alexandra sits quietly in-- notably--Calpurnia's chair in the kitchen with her face in her hands. Turning to Miss Maudie she declares,
'I can't say I approve of everything he does, Maudie, but he's my brother, and I just want to know when this will ever end....It tears him to pieces. I've seen him when--what else do they want from him, Maudie, what else?....I mean this town. They're perfectly willing to let him do what they're too afraid to do themselves--it might lose 'em a nickel. They're perfectly willing to let him wreck his health doing what they're afraid to do, they're--'
Miss Maudie cautions Alexandra to be quiet lest the other women hear her. She comforts Alexandra,
'Whether Maycomb knows it or not, we're paying the highest tribute we can pay a man. We trust him to do right. It's that simple.'
The "We" of whom Miss Maudie speaks are the people in the town "who say that fair play is not marked White Only...a fair trial is for everybody...." Miss Maudie lets Alexandra know that Atticus is perceived as a Christ-figure; he does not "let this cup pass," but leads and sets the example of what a true Christian is while bearing the cross for others, unlike the hypocrites/Pharisees of the Maycomb Alabama Methodist Episcopal Church South Missionary Society.