Should the mother pay back the money she owes to the fortune-teller, whom she went to unintentionally, knowing that going to fortune-tellers is one of the grave major sins?

The mother is not obliged to give money to the fortune-teller, because the earnings of soothsayers are unanimously prohibited, and the soothsayer does not deserve them because they are compensation for a forbidden act. The Prophet, peace and blessings be upon him, forbade the payment to the soothsayer. The mother must stay away from fortune-tellers and turn to Allah to solve her problems.