You can run a one-node replica set in MongoDB to support MMS Backup, enabling backup of standalone servers by producing the oplog required for backup. To achieve this, you need to shut down and restart the mongod instance with the --replSet option, initiate a new replica set using rs.initiate(), and configure monitoring and two-factor authentication before installing the backup agent. With these steps, your standalone server is no longer isolated but backed up by MongoDB's MMS Backup service.