The most appropriate completion for the sentence would be: "But we're here to find clothes for you girls, not me."
The sentence "But we're here to find clothes for you girls, not me" is part of a conversation where Mama expresses admiration for some silky scarves and beaded necklaces in a store. However, she acknowledges that the purpose of their visit isn't for her to shop for herself but rather to find items for her daughters ("you girls").
The completion "clothes" is fitting because it contrasts with the accessories (scarves and necklaces) that Mama was admiring. It emphasizes that the main goal of their visit is to shop for clothing items specifically for the girls, redirecting the focus from the accessories that caught Mama's eye.