Which is more proper: studying at a non-mixed university in another country without a mahram, or studying at a mixed university in the country of residence with family, given the father's absolute refusal to discontinue studies?

Mixing in workplaces and educational institutions is forbidden, and it is not permissible for a girl's guardian to encourage her to do so. Similarly, it is not permissible for a woman to travel without a mahram (definition), based on the Prophet's (peace be upon him) saying: "(A) woman should not travel except with a dhī mahram." However, her remaining in a city without a mahram is not prohibited if she feels safe and observes Allah. If she travels with a mahram and stays in a safe place, adhering to Islamic guidelines, there is no harm. If the family insists on her studying, and there is no alternative, she should choose the lesser of two evils. Travel might be the lesser evil, especially if communication with a mahram is possible for reassurance and assistance. One should strive to increase their faith and seek righteous company.