They refers to Laban and to Rebekah’s mother.

Call the maiden, and ask her: ask her is literally “inquire at her mouth,” with emphasis on asking the person directly, not indirectly through someone else. This expression is used also in Josh 9.14; Isa 30.2. The sense is “We will call Rebekah and ask her what she thinks,” “We will call her and find out her opinion,” or “… what she wants to do.”

Quoted with permission from Reyburn, William D. and Fry, Euan McG. A Handbook on Genesis. (UBS Helps for Translators). New York: UBS, 1997. For this and other handbooks for translators see here .