A "moment of inattention" caused Tiang to steer over the centre line, and she then over-corrected the vehicle which fishtailed and hit two trees, Judge Edwards said.
"It was a momentary misjudgement on your part," she told Tiang, who wiped away tears in the dock.
"It was carelessness at the very lowest end of the spectrum."
Judge Edwards said the tragic outcome of accident was far greater than the error Tiang made, and that she did not see the need to punish her further with a fine.
Tiang was convicted and disqualified from driving for 12 months for each of the charges.
Tiang's father died at the scene and her mother died the next day in hospital. A grandmother remains in hospital.
Tiang was supported at the court by her family, including an uncle who is believed to work at the Malaysian High Commission.
The family was planning to leave New Zealand for Malaysia as soon as possible, and funerals for the two victims would be held there early next week.