Here are a few excellent articles to check out.
How Much of a Threat Is the Purported ‘Momo Challenge’ Suicide Game? - Snopes Fact Checker
How 'Momo', a global social media hoax about a paranormal threat to kids, morphed into a U.S. viral phenomenon - NBC News
HOW TO NOT FALL FOR VIRAL SCARES - Wired
Momo challenge: The anatomy of a hoax - BBC News