If you count also their sister properties including FB Chat and WhatsApp and Instagram. But Facebook the social network hasn't 2B monthly active user, as many left or rarely return.
"Our community now has more than 1.9 billion people, including almost 1.3 billion people active every day."
[1] https://www.facebook.com/photo.php?fbid=10103696225640981&se...
[2] https://i.imgsir.com/qePz.jpg
