Is what was published on Facebook about the appearance of phantoms and children to people true, and how can one cope with this fear despite adhering to prayer, reading Qur'an, and performing adhkar?

Allah knows best the veracity of what those who publish posts mention. To rid oneself of the feeling of fear, we advise reliance on Allah Almighty and having a good opinion of Him, and believing in divine decree (qada') and destiny (qadar). What helps with this is: supplication (dua'), contemplating Allah's mercy, frequently remembering Him, acquiring beneficial knowledge, repelling obsessive thoughts, and refraining from reading what provokes fears, especially if it is unreliable.