Necessity of a mahram to accompany a woman when she travels, even if it is a short trip
Question

                We live in the country. Sometimes I like to visit my uncle who lives in a city that is 50 km further than us. I have to use mixed transportation and go alone because my father thinks it is very expensive to use transportation. He leaves the matter of meeting my uncle or not up to me. There is no other place I can go to. I visit my uncle every 5-8 months. Am I allowed to travel without a mahram?.
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 trips and short trips, according to the majority of 
    scholars. Everything that is called travelling is forbidden for a woman 
    unless she has a mahram with her. 
Al-Bukhaari (1792) 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 a 
    woman unless her Mahram is with her.’ A man said, ‘O Messenger of Allaah, I 
    want to go out with such-and-such an army and my wife wants to go to Hajj.’ 
    He said, ‘Go to Hajj with her.’” 
Al-Nawawi (may Allaah have 
    mercy on him)said in Sharh Saheeh Muslim, explaining that travel here does 
    not refer to a specific distance:
Everything that is called 
    travelling, it is forbidden for a woman to do without her husband or a 
    mahram, whether it is three days, two days or one day, or anything else, 
    because of the hadeeth of Ibn ‘Abbaas, according to which the Prophet (peace 
    and blessings of Allaah be upon him) said: “No woman should travel without a 
    mahram.” This includes everything that is called travel. And Allaah knows 
    best.
End quote. 
And it says in Fataawa 
    al-Lajnah al-Daa’imah (17/339): It is haraam for a woman to travel 
    without a mahram in all cases, whether the journey is long or short. End 
    quote. 
Based on this, if this 
    distance is regarded by people in your country as travelling, then it is not 
    permissible for you to travel without a mahram. But you will be rewarded for 
    your intention, in sha Allaah, and you can maintain ties with your uncle by 
    telephone, and that will be sufficient in sha Allaah. 
And Allaah knows best.