Wa `alaykum As-Salamu waRahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Answering your question, Sheikh Ahmad Kutty, a Senior Lecturer and an Islamic Scholar at the Islamic Institute of Toronto, Ontario, Canada, states:
The Prophet, peace be on him, said: “It is not permitted for a woman who believes in Allah and the Last Day to travel a distance involving one whole day and night without the escort of a mahram.” (Muslim)
All the laws of Islam are based on infinite wisdom. The wisdom and purpose of the above statement of the Prophet (peace be on him) are undoubtedly intended to ensure the protection and security of women.
Based on their understanding of the above wisdom, a number of scholars and jurists have ruled that a woman can travel in the company of reliable women. This is the opinion of great Imams such as Malik and Ash-Shafi`i and has also been authenticated by later scholars like Ibn Taymiyyah.
The above view has also been supported by the practice of the wives of the Prophet (peace on him). During the time of the Caliph `Umar, he allowed them to go for Hajj in a group under the leadership of eminent companions such as `Utham ibn `Affan and `Abd al-Rahama ibn `Awf (may Allah be pleased with them all).
As the above journey was undertaken with the permission of `Umar and the knowledge of the companions of the Prophet (peace be on him) and since no one raised any objection against it, it amounts to almost a consensus of the companions.
Almighty Allah knows best.