A 15-year-old boy was stabbed to death outside an out-of-control Long Island house party Monday night, and the 70-year-old homeowner ended up being charged for allowing another reveler — her grandkid — to host the rowdy event, cops said.

Liam Delemo was stabbed around 10:25 p.m. when a fight broke out outside the private house on tree-lined Carlton Road in West Babylon, where between 90 and 100 teens gathered for the bash, Suffolk County Police said.

He was rushed to Good Samaritan Hospital Medical Center in West Islip, where he was pronounced dead, cops said.

Liam Delemo, 15, was stabbed to death outside of a West Babylon house party . Facebook

Bonnie Miranda, 70, who owns the home, was arrested and charged with a violation of Suffolk County’s Social Host Law for permitting her grand

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