Although the Gospels do not specifically recount the appearance of the risen Christ to his mother, it is taken for granted by Saint Ignatius of Loyola, who quotes in his Spiritual Exercise nr. 299: "The Resurrection of Christ our Lord: His First Appearance: He appeared to the Virgin Mary; which, although it is not said in Scripture, is taken to be implied when it says that He appeared to so many others. For Scripture assumes that we have understanding, as it says: "Are you also without understanding?"
Moreover, there are hints of this in the Gospels, as John Paul II reminded us in a catechesis in 1997.