What is the ruling on a group of young men and two young women, one of whom is without a mahram, traveling for tourism and information gathering, knowing that accommodation and transportation will be shared?

A woman's travel without a mahram is forbidden (haram) and constitutes a journey of disobedience. It is not permissible to accompany her on this journey, as doing so would be an endorsement of her disobedience, and this contradicts the principle of enjoining good and forbidding evil. The obligation is to refrain from this journey as long as this woman is present, out of obedience to Allah.