Rather than looking "around her time of the quiz", it can be more informative to work out the student's IP address, and then you can see all the log entries (apache web logs, PHP logs, and Moodle logs) for the entire time period (without the noise from all th other users) and get a full picture of what happened.
The Database transaction aborted automatically is mostly a symptom, rather than a clue to the cause. Is it possible that the user's login session ran out in the middle of the quiz? (In the full logs, look for redirects to login/index.php.)
The Database transaction aborted automatically is mostly a symptom, rather than a clue to the cause. Is it possible that the user's login session ran out in the middle of the quiz? (In the full logs, look for redirects to login/index.php.)