Chaucer's "holy blissful martyr" is a literary-historical allusion to Thommas a Becket. Option B is correct.
Thomas Becket was Archbishop of Canterbury from 1162 until he was murdered in 1170. He is venerated as a saint and martyr by both the Catholic Church and the Anglican Communion.
He was murdered by followers of king Henry II in Canterbury Cathedral since they were in conflict over the rights and privileges of the Church.