No, none of you get US citizenship. You might be approved for an immigration visa to enter the US, and after entering on the visa, settling in the US, the green card (proof of legal permanent residency status) will be mailed in care of sponsor in a few weeks to months after arrival.
Once your mother's priority date becomes current, her brother must prove he meets earnings requirements for himself, all his dependents, plus his sister & any of her dependents included in the petition. Then interviews at the US consulate nearest your mother's home are scheduled, as are health exams, biometrics, etc. IF approved, an immigration visa is issued, and she has 6 months to enter US with her approved dependents listed on the petition (if any).
After receipt of green card, immigrants must reside in US for a minimum of 5 years before they might become eligible to apply for naturalization. So no US citizenship or passport for many years to come, and a lot of regulations to meet to qualify to apply.