In the passage from The Horse Dealer's Daughter, the third-person narrator is providing Mabel's thoughts as she prepares to take her own life. As the only girl among the siblings, Mabel understands that she is at an extreme disadvantage now that their father has died.
Mabel shows her determination, and the passage illustrates what the narrator calls her family's "animal pride" in this passage. Earlier in the story, it has been clearly shown that each brother planed to live his own life as he saw fit, and none of them are especially concerned about her future plans.
Painfully aware of her very limited prospects, Mabel decides to walk into the lake:
Still she would not cast about her. She would follow her own way just the same. She would always hold the keys of her own situation.
Twice the narrator refers to "the end," unmistakably indicating the finality of her decision: "Now, for Mabel, the end had come." All the things poverty has forced her to do have come to an end. She will now join her dead mother.