It is not lawful for a woman who believes in Allah and the Hereafter to undertake a day's journey except in the company of a Mahram. (Using translation from Muslim 1339b)
عَنِ النَّبِيِّ ﷺ قَالَ لَا يَحِلُّ لِامْرَأَةٍ تُؤْمِنُ بِاللهِ وَالْيَوْمِ الْآخِرِ تُسَافِرُ يَوْمًا إِلَّا مَعَ ذِي مَحْرَمٍ