The grandmother is seemingly irredeemable in O'Connor's "A Good Man is Hard to Find." I suggest the previous answer misses the point. There's nothing good or redeemable about the grandmother. She is totally unlikeable. She is racist, bigoted, superior, negative toward everyone. I don't know about other readers, but I've never met anyone that sees her as redeemable at the end. That is a misreading.
What would make her redeemable at the end? The story tells you: there's no reason for speculation and applying one's own sentimentality to her. The story says:
"She would of been a good woman," The Misfit said, "if it had been somebody there to shoot her every minute of her life."
That's what the story says. Anything else is putting your own personality into the interpretation of the story and is absolutely irrelevant.
That's what it would have taken for this woman to have been a good woman. She was absolutely worthless. Only a man ready to shoot her every minute of her miserable life could have convinced her of the truth of existence.
And that's the point. O'Connor did want to say that God's grace was for everybody--even this absolutely miserable and irredeemable woman.
How does The Misfit know this would have worked? Because his putting a gun to her head brought about an epiphany in her. That's what it took.
The grandmother is an interesting character in this story. She seems to be a good woman already, in many ways, but she is also quite racist, elitist, and manipulative. Because she is a grandmother, though, this seems to make her redeemable in the end to most readers. A reader cannot help but feel sorry for her because of her age and because she mistakenly leads her family to an incorrect location of her old childhood home that is actually in another state.
In the story, the grandmother displays many bad traits. She is critical of her daughter-in-law and babies her son, even though he is a grown man. She makes a negative comment about an African-American child she sees, which tells the reader she is a racist. She is also an elitist (she feels she is better than others at times). She also believes she is superior morally to others, but this is obviously not true, in part because of what is mentioned above. eNotes states:
She demonstrates racist behavior by calling a poor Black child "a pickaninny ... Wouldn't that make a picture, now?" and she reveals a superior moral attitude.
In the end, the grandmother is "saved" after reaching out to touch the Misfit. O'Connor wanted to show her belief that all are redeemable through God's grace (eNotes).