Sayyidina Abu Saeed (RA) reported that Allahs Messenger (SAW) said, It is not lawful for a woman who believes in Allah and the Last Day that she travel (alone) on a journey of three days except that she is accompanied by her father, her brother, her husband, her son or a mahram (besides them).
[Ahmed 41515, Muslim 1340, Abu Dawud 17, Ibn e Majah 2898]