I guess you can blame Merope Gaunt for the trouble caused by her son at Hogwarts. She was only however half the blame for his parentless Childhood and him being sent to a muggle orphanage because as soon as she got pregnant she let the love potion wear off her muggle lover and told Tom Riddle Sr. that she was a witch and so he up and left to the Riddle House in Little Hangleton to live a merry life and tradgic death. She had died not long after Tom was born. Only long enough to name him Tom after his father and Marvolo after his grandfather. So even if she died at birth, he could've still had a father but he left them.
Soon after birth. Tom was sent to a muggle orphanage where havoc erupted as he grew older. Tom had no idea he was a wizard and had no control over his magic but used it to torture the kids there. That was until the day Albus Dumbledore arrived at the orphanage to inform Tom of his blood and offer him a place where he can learn to control his magic and a place to fit in, a place called Hogwarts. The Answer of course was yes.
So Tom boarded the gleaming scarlet steam engine Hogwarts express on Platform 9 and 3/4 where ahead his magical life begins and so does our story; the deeper story of Lord Voldemort.
A Basilisk is loose in the castle, the chamber is open and a girl is killed. Who's to Blame?