Mahram of Married Slave In case of Hajj & Umrah

Who is the Mahram of Married Slave Women when it comes to her performing Hajj or Umrah as per Fuqaha? Can A Married Slave women perform Hajj and Umrah along with her Master and can the Master become or be considered Mahram for Hajj or Umrah if her husband due to some reason is unable to perform Umrah or Hajj with her? **I prefer to especially know the Ahkaam From Hanbali Madhab**