Is it permissible for a woman to travel a distance of 50 km to visit her uncle's house via mixed transportation and without a mahram, if her father believes that transportation costs are expensive and gives her the choice between going alone or not going, bearing in mind that she visits them once every 5 to 8 months?

The authentic Sunnah (definition) indicates that a woman should not travel except with a mahram (definition). This applies to both long and short journeys according to the majority of scholars. Anything that is considered travel is forbidden for a woman unless she is accompanied by a mahram. Al-Nawawi said: "The conclusion is that any journey, regardless of its length—whether three days, two days, one day, a barid, or anything else—is forbidden for a woman without her husband or a mahram." The Permanent Committee for Scholarly Research and Ifta stated in its fatwas: "It is absolutely forbidden for a woman to travel without a mahram, whether the distance is short or long." If the distance is considered travel in the questioner's country, then it is not permissible to travel without a mahram, and she should suffice with a phone call.