The crowns shall be … for a memorial. The crown was to be taken from Joshua's head and deposited in the temple as a memorial of this prophecy, and of the zeal of those who had come from far to bring offerings to the Lord, and likewise of the hospitality of Josiah, who had received them into his house.
That such "gifts" were dedicated in the temple is well known. Helem is the same as Heldai (verse 10), whether he bore both names, or whether, as is probable, this is a mere mistake of a copyist. To Hen.
The Authorized Version considers this as a proper name. In this case it would be another name for Josiah. But it is really an appellative, and the rendering should be, "for the kindness of the son of Zephaniah."
The crown would be also a memorial of his kindness in receiving and entertaining these exiles (comp. Matthew 10:41). The LXX. explains the names as in verse 10, though not quite in the same way, εσται τοῖς ὑπομένουσι καὶ τοῖς χρησίμοις αὐτῆς καὶ τοῖς ἐπεγνωκόσιν αὐτὴν καὶ εἰς χάριτα υἱοῦ σοφονίον καὶ εἰς ψαλμὸν ἐν οἴκῳ κυρίου, "The crown shall be to them that endure, and to its good men, and to those that have understood it, both for a favour to the son of Sophonias, and for a psalm in the house of the Lord."