From the CE article
Feast of the Assumption:
St. John of Damascus (P.G., I, 96) thus formulates the tradition of the Church of Jerusalem:
St. Juvenal, Bishop of Jerusalem, at the Council of Chalcedon (451), made known to the Emperor Marcian and Pulcheria, who wished to possess the body of the Mother of God, that Mary died in the presence of all the Apostles, but that her tomb, when opened, upon the request of St. Thomas, was found empty; wherefrom the Apostles concluded that the body was taken up to heaven.
It is not absolutely clear whether by “all the Apostles” he means all the Apostles then living, or all the Twelve (minus Judas plus Matthias), or some other configuration of Apostles. I think it is reasonable to take the text at face value, which would mean St. James the son of Zebedee was still living.
Herod had St. James killed about 11 years after the Crucifixion of our Lord (cf. Acts 12:1-2), so if we take the above to be accurate, that would mean our Lady did not die any later than 11 years after her Son’s death.