After a failback operation in various disaster recovery scenarios, including for virtual machines, the next possible actions typically involve either confirming the failback or reversing it. 'Undo failback' allows for the reversal of the failback operation if any issues are detected, while 'Commit failback' finalizes the process, ensuring that the virtual machines are properly stabilized in their original location. Therefore, the appropriate next actions after completing a failback are 'Undo failback' and 'Commit failback'.