In the movie version of Deathly Hallows, part 1, Dobby takes the wand of Draco's mother shortly after Harry takes Draco's wand. Then in Deathly Hallows, part 2, Draco says he is using his mother's wand. How did Cissy get her wand back in order to lend it to her son? Dobby disapparated pretty much immediately after taking it. Did Cissy own 2 wands? No other wizards or witches (that I know of) have 2 wands of their own, so this seems unlikely.
According to a Harry Potter "Q & A" Page,
Dobby disarmed her but left the wand behind, as it was not in his possession when he died. If it was, Harry would have taken it, but Harry only had three wands -- all of which were examined by Ollivander -- but they belonged to Draco, Bellatrix Lestrange, and Peter Pettigrew. http://harrypotter.answers.wikia.com/wiki/Why_does_Draco_Malfoy_get_his_mothers_wand_when_Dobby_disarmed_her_in_deathly_Hallows_Part_1
Also confirmed as a *possible expaination here:
In Harry Potter and the Deathly Hallows: Part 2, Draco Malfoy uses his mother's wand during the Battle of Hogwarts, despite being taken away by Dobby in Deathly Hallows: Part 1. It is possible that Dobby dropped it while teleporting. http://harrypotter.wikia.com/wiki/Narcissa_Malfoy%27s_wand