Does the monthly allowance from which the student spends necessitate Zakat?

Zakat is not obligatory on a monthly allowance immediately upon its receipt. Rather, it becomes obligatory if a full year (hawl) passes while it reaches the nisab (minimum threshold) on its own, or when combined with other funds owned by the sister asking the question. The proof for this is the statement of Ibn Umar: "Whoever benefits from money, there is no Zakat on it until a full year passes over it," and the statement of Aishah: "There is no Zakat on money until a full year passes over it."