With transcendentalism, who possesses the power to transcend the material world to find meaning in life?

The correct answer here would be all people.

Transcendentalism is a literary and philosophical movement that originated in the United States of America as a reaction to the prevalent intellectualism, philosophy, spirituality. One of the most prominent people associated with the movement is Ralph Waldo Emerson in whose essays we see that all people are capable of transcending the physical senses with free will and intuition into deeper spiritual experience.