Is it essential for a woman to have a mahram with her for a short journey?
Question

                Must I have a mahram with me while traveling between Cairo and al-qalyoubiyyah (about 100km)? My father has passed away and my only brother lives close to his university, and he does not come except in the weekends. This will delay many important matters of mine.
Praise be to Allah.The saheeh Sunnah indicates 
    that it is not permissible for a woman to travel without a mahram. This 
    includes both long and short journeys, according to the majority of 
    scholars. Everything that is called travelling is forbidden to a woman 
    unless she has a mahram with her. 
Al-Bukhaari (1729) and 
    Muslim (2391) narrated that Ibn ‘Abbaas (may Allaah be pleased with him) 
    said: The Prophet  (peace and blessings of Allaah be upon him) said: “No 
    woman should travel except with a mahram, and no man should enter upon her 
    unless there is a mahram present.” A man said: O Messenger of Allaah, I want 
    to go out with such and such an army, and my wife wants to go for Hajj. He 
    said: “Do Hajj with her.” 
Al-Nawawi (may Allaah have 
    mercy on him) said, explaining that travel here does not refer to a 
    particular distance: 
What is meant is that 
    everything that is called travel is forbidden to a woman without a husband 
    or mahram, whether it is three days or two days or one day or twelve miles 
    or anything else, because of the report of Ibn ‘Abbaas (may Allaah be 
    pleased with him), “No woman should travel except with a mahram.” This 
    includes everything that is called travelling. And Allaah knows best. End 
    quote. 
Al-Nawawi, Sharh Muslim 
    (9/103). 
In Fataawa al-Lajnah 
    al-Daa’imah (17/339) it says: It is haraam for a woman to travel without 
    a mahram in all cases, whether the distance is short or long. End quote. 
See also the answer to 
    question no. 101520. 
What counts here is what is 
    customary among people. If people regard it as travelling, then it is 
    travelling, and it is not permissible for a woman to set out on such a 
    journey except with a mahram. 
Going from al-Qalyoobiyah 
    to Cairo is not customarily regarded as travelling, rather there are many 
    areas in al-Qalyoobiyyah to which it is easier and closer to travel than 
    between one part of Cairo and another. 
Based on this, there is 
    nothing wrong with going from al-Qalyoobiyyah to Cairo to attend to your 
    needs without a mahram. 
And Allaah knows best.