Is it permissible for an unconsummated married woman to travel for Hajj or Umrah alone with a trustworthy group, if her husband is waiting for her in Mecca to be her mahram during the performance of the rituals?

The answer is summarized in the following points:

There is a difference of opinion among scholars regarding a woman traveling with a trustworthy company without a mahram. The preponderant opinion is that it is permissible for a woman to travel for the obligatory Hajj with a trustworthy company if she is safe from fitnah. Safety from fitnah is determined based on the time, place, means of travel, companionship, and the woman's condition, and it varies according to individuals, times, and circumstances. There is no harm in the sister traveling if she is safe from fitnah with the company, and in the time, place, and means of travel, and if her husband gives her permission.