Question

What major even occurred in Frankenstein’s life when he was 17 years old

Answer 1

His mother dies, due to the fever she had been diagnosed with, also known as "Scarlet Fever". At that time, Frank was preparing to go to the University in Ingolstadt. Hope this helps.

Answer 2

His mother catches scarlet fever and dies at the time that he was preparing to go to university in Ingolstadt.