This is how it was ordered by Prophet Muhammad (p&buh).

It is very rare that one does not have a mehram at all as the list of mehram is quiet long and not limited to (blood brother, father and husband).

Grand Father (paternal and maternal), Brother of Father and or Mother, Sons of brother/s, or sister/s, step sons and brother from foster relation are also mehram

If one does not have any of the above relations and she is financially capable then she can nominate one person on her behalf and May Allah accepts the ajar equal to performing a Hajj herself.

The whole idea is to perform this very important ritual of Islam BUT on the terms which Allah accepts not as per our own desire as this effort is for Allah sake and should be the way Allah ordered.

Mainly the travelling alone for women is not allowed at all and Hajj does involves travel.

Allah knows the best & May He forgive our limited understandings and mistakes knowingly and unknowingly and Guide us to the straight path. Aameen