The other worker of this mod Bloodshot is going to make an update for 1.10 fixing all the bugs but for now Mo Creatures is on the backburner because he's working on an update for Sponge/Grief Prevention which he also made/works on. This mod isn't dead but it is dormant for now.
That's ironic. We specifically didn't move to Sponge because we knew there would be large delays in updates. We moved to forge only from cauldron and managed to cover mob griefing through various mods. This mod might not be dead, but my private server definitely is since we are regularly falling 2 and 3 releases behind because of things like this.