Question

The shallow was going to die. He bade good bye to the happy Prince. Join into adverbial clause

Answer 1

Question after minimal corrections:
The shallow was going to die. He bade good bye to the happy Prince.
Join using adverbial clause.

Adverbial clauses are such clauses which acts like an adverb. It generally tells us why an action was done.

Answer:
The shallow bade good bye to happy Prince as he was going to die.

The adverbial used in the answer is $\underline\bold{as\:he\:was\:going\:to\:die}$