Bonus DVD's were the 1993 masters.
All Laserdisc and home video releases before DVD were the 1981 version, when the "Episode IV A New Hope" title was added. Sound mixes have varied depending on what elements have been used. Ben Burtt did another mix just for home video in the mid 80's. Another home video sound mix was done in 1993, (the first official THX certified release) that incorporated elements from the 70mm mix.