What is the ruling on a woman traveling if her first mahram takes her to the airport and another mahram receives her, given that it is often difficult to find a mahram?

The majority of scholars do not permit a woman to travel without a mahram unless there is a necessity. Some of them have allowed it when there is no fear of fitnah. If you are compelled to renew your residency permit, and a mahram is not available, and your journey is safe, then there is no objection to following the opinion that permits such travel in this situation.