A dozen named groups and individuals will be purged from the social network, it said.
Holly Eastall says she felt suicidal after being falsely accused of abuse following her baby's death.
Milly and Toby Savill were on Santorini when the buggy they were in fell into a ravine.
Former beauty queen Sophie Gradon was found dead by her boyfriend who killed himself days later.
Police rest days are cancelled as more than 1,000 officers are deployed in London.