Who was the old woman near the end?

It symbolized how inevitable the events were. If the protagonist's "mother" hadn't jumped herself, she would have been pushed. It was the relentless march of history that ensured this particular outcome.

Starting with the younger woman and her husband, Kang Do revisits them again. She was the one who offered her body to him to try to spare her husband's hand. She now supports her disabled husband, taking abuse and resentment from him. When Kang Do comes to them thinking they have kidnapped his mother she tells Kang Do that if it were legal she WOULD kill him, and she would crush him and drag his body with her truck.

SPOILER HERE...

At the end, when he realizes that the mother he has lost was a woman who sacrificed her life for revenge due to the loss of her son... Kang Do, who also we now see is capable of attachment and love, does grieve. She has gotten what she wanted, which was to make him revisit all the cruelty he has done.

He revisits the first couple (yes I see a rhythmic significance here too, they are the first couple we see him torture and they are the last couple we see him with). The woman who said she wished she could crush him, he watches as she feeds her husband and gets ready to go to try to make money.

Kang Do gives her what she wished for. He trusses himself beneath her truck, and without realizing it, she drags him to his death, smearing his blood all along the way.

The billboard in the last scene was particularly touching. A man, in a similar body position, water skiing on vacation. Perhaps a sign of Kang Do's redemption?

This brings me back to the older woman. She came back to where her son was pushed off to break his leg, and she was one of the few who knew of Kang Do's new found family.

She comes at the end I think to show us there is no way to reverse all this. The mother who has gone to all this length for revenge actually feels sorry for her son's killer and tormentor. She realizes that he truly suffers as well. For a moment it seems she will "save" him. But the older woman appears behind her, I think as a reminder of all the pain and destruction that can never be fixed.

Her son was the one who wondered who would take care of his mother, who was left a beggar, and then who died in his elderly mother's arms from the knife. She is left all alone like the other elderly woman who mourns and weeps at the small grave without knowing Kang Do is the reason for his death. The older woman then spent time with her son before he died from his knife wound, and would have been one of the few who knew of Kang Do's "mother" so it makes sense she herself went back for revenge.

Thus, there was no going back. There is that moment where event the psychopath is sympathetic, and after she has gone to such lengths for revenge her revenge must seem hollow. But she still jumps, just before the older woman could push her. The suicide would have been a murder, because the older woman was truly going to push her over just like her own son was pushed. To me this signifies that there was no way for Kang Do to turn around what he had done in life. He takes responsibility for his actions for the first time in the film, but just like his victims it is too late to change what is happening to him.

In the end, everyone suffers and loses, with the only hope being left on the poor woman who is unbeknownst to her, getting the revenge she wished for by dragging Kang Do beneath her truck.

The older woman is spared committing murder by a split second only which I think signifies that while it seems like this is just revenge from one dark and angry mother... in a larger sense it was what was going to happen to Kang Do because of what he chose to make his life about.

I found myself feeling bad for him, despite it all. There really wasn't anyone in this film who wasn't a tragic figure or a victim. And the consequences were not even or fair for anyone.