This error in your event log is coming from the FSMO server (server A) trying to replicate to DNS on server B, then B trying to replicate to DNS on server C.
Go into the dns mgr snap-in for the other two machines and remove the server C (crashed server) from the ‘allow replication to’ list. Also, you may have server B forwarding to server c, remove that reference also.
This will stop that particular error, but does not remove it from your AD. There, you will have to remove it in your ‘User & computer’ mgr. snap-in