I'm not saying the revenging kin are the cause of her death. I'm saying they're coming after her for revenge can be a complicating factor that adds to her jeopardy and enhances the dramatic tension. The King can get the satisfaction of the kill, but he's not the only one trying to kill her.
The reason I emphasize using the revenge cycle is because it is one of the most dependable plot tropes in drama. And that is so because it mirrors one of the most compulsively repetitive motifs in human history. I would venture to say it's a plot device that cannot not be developed and paid off with further scenes if it is an inciting motive in a plot.