Complex sentence: Shrimati Rukmini Devi Arundale pioneered the setting up of the Board, with its Headquarters at Chennai, and guided it, for nearly twenty years till her demise in 1986.
Split into simpler sentences: Shrimati Rukmini Devi Arundale pioneered the setting up of the Board, with its Headquarters at Madras. She guided the activities of the Board for nearly twenty years till her demise in 1986.