Draco was taking a much needed break from fighting with the contents of the Malfoy Private Library. Several of the tomes--including most of the highest importance--refused to leave the Manor, even under the care of the family head.
He cursed as he took a long draw of the scotch, which was the same time the house elf appeared--the one his mother had charged to inform them when Voldemort attacked the Ministry. He dropped the glass, which shattered on the floor. Draco ordered the elf to clean it up, he wasn't going to let the floors be damaged, even though he was taking a temporary leave from the place.
He apparated to Astoria and told her about the elf.
Once they were ready to leave for Hogwarts, Draco ordered the Manor to seal itself. He didn't expect it to be able to hold itself against Voldemort. But maybe it would prevent the bastard from getting the valuables that they couldn't bring. Maybe.