What is the title of one of the earliest morality plays and who composed it?

The title "Ordo Virtutum" by Hildegard von Bingen is indeed one of the earliest and most significant examples of a morality play. This work, composed around 1151, is notable for its unique blend of drama and music. It features a series of personified virtues and vices that illustrate the struggle of the soul to attain virtue and salvation. Hildegard von Bingen is recognized as a pioneering figure in medieval music, and her contributions to both music and theology greatly influenced the development of liturgical drama.

The context of the other choices contributes to the clarity of "Ordo Virtutum" as the correct answer. "Everyman" is also a significant morality play, but it is often attributed to an anonymous author and appears later than Hildegard's composition. "Allegory of Virtues" does not have a well-documented existing work under that title by Leonin, and "The Devil's Crown" by Perotin is not recognized as a morality play; rather, it pertains to other thematic areas in medieval music. This further underscores the historical importance of Hildegard's piece within the framework of early morality plays.