A secret (not realistic) 4th option.

So this is more of a hypothetical because the only ones with knowledge in game would be the M9 I guess. But if the gods' can't fight Predathos, and the Gods can't fight Tharizdun, why not just release Tharizdun and have it fight Predathos in a kaiju battle. This is more from the gods perspective I guess because their current option are run, get eaten, become mortal. At the very least releasing tharizdun presumably buys them time to escape or maybe tharizdun can defeat predathos.