Prohibiting Woman from Traveling Alone
Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah صلى الله عليه وسلم said, "It is not permissible for a woman who believes in Allah and the Last Day to make a journey of one day and night unless she is accompanied by a Mahram (husband or any other relative to whom she is prohibited to marry).''
[Al-Bukhari and Muslim].
Commentary: This Hadith offers three points. First, it mentions a twenty-four hour journey. 'Ulama', therefore, say that the time limit matters little and the real point is the length of distance to be called journey. A woman is not allowed to travel unless she is accompanied by her husband or a Mahram.
Secondly, Hajj is obligatory on her provided she has no financial problem. If a woman has no husband or Mahram, Hajj is not obligatory on her. Neither can she go for Hajj with a group of women, whether for Hajj or any other purpose.
Thirdly, the term Mahram, apart from husband, applies to all of her male siblings whom she cannot marry; these include the father, the son, the brother, the nephew, the son-in-law and the foster-father. She cannot travel with anybody but with any of these.