Is the Obligation of Hajj Waived for a Woman Who Cannot Find a Mahram to Travel With Her?

Yes, the people of Ilm (Islamic knowledge) mentioned - Allah said: "for whoever is able to find thereto a way" [al-'Imran: 97]. So, if a woman does not have a mahram, she is not able to, and Muslim scholars considered her to be incapable of performing Hajj.