Ghost could've gone to Mathura Central Jail and create some havoc there. With the way law is being handled in the world can assume ghost of some previous convict executed is doing things - at least until D shows up, cause she presumably owns that place too.
Skeleton under the office was taken from Drishyam. This track reminds me of a Madhuri movie (Anjam ??) where she is falsely convicted by SRK (antagonist i think) and goes through a lot of torture.