Praise be to Allah.
But the scholars made an exception from that in the case of obligatory travel on the part of an individual woman, such as migration from the land of kufr to a Muslim land.
Imam al-Nawawi said: The scholars are unanimously agreed that she should not go out for travel other than Hajj and ‘Umrah unless she has a mahram with her, except in the case of migration from dar al-harb (non-Muslim lands). They are unanimously agreed that she must migrate from there to a Muslim land even if she does not have a mahram with her. The difference between the two is that her staying in the kaafir land is haraam if she cannot practice her religion openly and fears for her religious commitment and for herself.
End quote from Sharh Saheeh Muslim, 9/104
Abu’l-‘Abbaas al-Qurtubi said: There is consensus that she is obliged to travel without a mahram if she fears for her religious commitment and for herself.
End quote from al-Mufhim lima Ashkala min Talkhees Kitaab Muslim, 11/6
That is because adhering to the commands of the faith is obligatory, and whatever is essential to doing something obligatory is also obligatory. This was stated in Mataalib Ooli al-Nuha, 3/433
Based on that, if you are not able to practice Islam fully in that land in complete freedom, or you fear for your religious commitment and for yourself because of temptation and confusion, then you have to migrate to a land where you will feel that your religious commitment and your life are safe. The interests of religion take precedence over obedience to parents, as Allah says (interpretation of the meaning):
“But if they (both) strive with you to make you join in worship with Me others that of which you have no knowledge, then obey them not; but behave with them in the world kindly”
But if you are able to practice Islam and you are living in that land with complete safety, then migration in this case is mustahabb and not obligatory. See the answer to questions no. 47672 and 13363.
In that case it is not permissible for you to travel for two reasons: not having a mahram, and not having the permission of your mother to travel.
Al-Bahooti said: He should not travel for a mustahabb purpose except with their [parents’] permission…, because honouring parents is an individual obligation (fard ‘ayn), which takes precedence over that which is mustahabb and that which is a communal obligation (fard kifaayah).
End quote from Kashshaaf al-Qinaa‘, 6/322
And Allah knows best.