A. Hopefully you’ve got a documented social media policy in place that the employee has signed, and addresses this issue. If not, implementing a social media policy is a great place to start.
You should schedule a meeting with this employee to discuss the matter, allowing them to bring a support person if they chose to do so, and referring back to any relevant clauses in the employee’s contract and the social media policy. It would be a matter of putting the allegation(s) and any supporting evidence to the employee and providing the employee with the opportunity to respond.