Is it better for the mother to give the money from the sale of her land to her husband to pay off his debts, or to use it for 'Umrah, or to prepare her daughter who is about to get married?

If the mother has not performed the 'Umrah (definition) of Islam (the obligatory 'Umrah), she must hasten to perform it immediately, prioritizing it over settling her husband's debt or helping to prepare her daughter for marriage, as neither of these is obligatory upon her.

However, if she has already performed the 'Umrah of Islam, she may contribute to settling her husband's debt, even with a loan, or assist in preparing her daughter. Both of these are good deeds. She must not go out for a non-obligatory 'Umrah unless accompanied by a husband or a mahram (definition).