Is the wife entitled to demand her private money (18,000 riyals) from her husband, knowing that he spends on all the household and children's needs, as well as her medical treatment and delivery expenses, and that her salaries are spent on her or on assisting her family?

What is obligatory upon you is to pay your wife's debts and to spend on her and your children with fairness. You are not entitled to reclaim what you spent on her education because it was a donation. Her earned money from her work is her exclusive right, and she is not obliged to spend on the household, unless you stipulated that she gives you a portion of her salary in exchange for your permission for her to work. You have the right to prevent her from working unless her going out to work was a stipulated condition in the marriage contract.