The unnamed grandmother in the short story "A Good Man is Hard to Find" by Flannery O'Connor shows many elements of conventional middle-class southern values.
Her first major social value is the importance of the concept of being a "lady." She laments the decline of good manners and the difficulty of finding people who follow the conventional codes of polite behavior, codes including speech, dress, and gesture (holding doors, etc.). She tends to identify following these external values with moral goodness, even though the two are not actually related. Particularly ironic is her concern for dressing well at all times so that if she dies she will appear a ladylike corpse, a gruesome concern made especially ironic by the end of the story.
Next, her conventional religious values emphasize outward conformity to religious ritual rather than inward goodness. This is especially brought to the forefront in her conversations with the Misfit, who actually takes Christianity somewhat more seriously than she does, in the sense of dealing with it as a real issue rather than a sort of social ornament.
Finally, she accepts conventional gender roles, on the surface accepting masculine power and superiority but simultaneously not listening to the advice of the male characters in the story.
The grandmother's behavior and her speech expose a number of social and religious conventions. The first is that she expects, being a senior citizen and a mother, that her son will listen to her and, out of respect, acquiesce to her suggestion that they travel to Tennessee. This request is, however, ignored even when she points out the danger of traveling to Florida.
Once they are ready to leave, she illustrates another old-fashioned social convention: to get all dressed up for a trip. She puts on attire that, she believes, will make her look like a lady if they should have an accident and she's found dead on the highway (this line of reasoning isn't quite as traditional). Another social practice she exercises is to point out the scenery while they are driving. The trip, to her, should be an educational venture and she makes a point of talking about the sights and pointing out places of relevance to her grandchildren.
In addition, it is clear that the grandmother believes in the principle of respect, not only for others, but also for the environment. She, for example, stops the children from disposing of their litter through the car window and also regularly complains about their lack of respect for her. She vents her frustration about this by admonishing her son, Bailey, about the fact that he does not show any respect for his state and saying that "children were more respectful of their native states and their parents and everything else."
In their encounter with the Misfit, the grandmother displays the religious conventions she believes will convert him. She clearly believes that prayer would help him and that he would find redemption and therefore change his ways. She believes that if she can appeal to whatever goodness he still has left in him, he will reconsider. She is, though, made aware by the insidious criminal that he had already considered religion as a way out for him but could not find any solace or redemption. Her appeal has no effect.
Even the grandmother's appeal to courtesy (another social convention) has no effect on the Misfit. She cries out that a man "ought not to shoot a lady," but that doesn't work with him. He cannot be rescued or turned by convention, whether social or religious, for he is beyond anything. He is a hardened criminal and a remorseless, cold-blooded killer who forgets the wrongs that he has done.
It is markedly ironic that the grandmother is the one responsible for exposing herself and her family to this danger and, just like the Misfit, does not realize or acknowledge the huge mistake that she had made.