I don't think "Now Is The Hour" is Maori, it's a generic New Zealand one.

They used to have a nice ritual when the departure was by ship. People on the ship would biff toilet rolls down to the quay holding the end, so there were hundreds of streamers held at each end. They'd all sing "Now Is The Hour" as the ship moved off and broke the TP. Did that for my grandma at Auckland quayside after she'd come over for my graduation in 1971.

My favourite farewell songs are Scottish ones not mentioned yet: "We're No Awa Tae Bide Awa" and "Happy We've Been A Thegither".