Can you correct my grammar?
On the night of December 16, 2009, I was awoken by my mother, only to find her crying hysterically. I jumped out of bed in less than a second, assuming it was about my brother who just received his driver’s license hence in a car accident.
The structure of the last part isn’t right. You may mean:
“I jumped out of bed in less than a second, assuming that my brother, who had just received his driver’s license, had had an accident.”
(Very fussy comment which you may wish to ignore: To me, it sounds faintly odd to say “I was awoken by my mother, only to find her crying hysterically”. This is because “only to find her…” usually implies some action on the part of the finder in order to make the discovery (such as going into a room, telephoning someone, or whatever it might be). In this case the “finder” was asleep, so could not have made any such action. Therefore, I would probably just say “I was awoken by my mother, who was crying hysterically”.)