It is generally assumed that our Lord only raised three persons from the dead - this young man of Nain. the little daughter of Jairus the ruler, and Lazarus of Bethany. But such an assumption is purely arbitrary.
We have before called attention to the vast number of miracles worked by Jesus during the two years and a half of the public ministry not reported by the evangelists at all, or only glanced at in passing. There were, most probably, among these unreported miracles several instances of men, women, and children raised from the dead. St. Augustine, in one of his sermons (98.), specially calls attention to this in his words, "of the numerous persons raised to life by Christ, three only are mentioned as specimens in the Gospels."
He had compassion on her. In this instance, as in so many others, our Lord's miracles were worked, not from a distinct purpose to offer credentials of his mission, but proceeded rather from his intense compassion with and his Divine pity for human sufferings.
(Excerpt from the Pulpit Commentary)