Are the expenses for the second semester, which the university requests in advance, considered a debt, or can they be paid after performing the Hajj pilgrimage?

There is no harm in performing Hajj with one's mother at her expense; this is a form of showing dutifulness to her. The debt that would prevent its owner from performing Hajj must meet the following conditions: it must be due for immediate payment, the creditor must grant permission, the debtor must not have sufficient funds to repay it, and the Hajj must be performed with the debtor's own money.