Diane Smulligan said her son was addicted to prescription pain medication and did not have a home.
"He was trying to get his life back together, but it was hard for him to hold a job," she said in an interview.
Smulligan was one of three people in the region whose deaths were blamed on the frigid weather.
The Philadelphia Medical Examiner's office told Smulligan's family he died of hypothermia.
Two elderly residents in Delaware County - 89-year-old Allan Jameson and 92-year-old Alice Mae Brown - also died from the cold.
A third Delaware County person had been suspected of dying from exposure. But on Friday, the Medical Examiner's Office in Delaware County said the 64-year-old's death was from a head injury. Officials declined to identify the man, who was found outside, or give further details about his death.
Smulligan, who was the eldest of five siblings, grew up in Hazleton and graduated from New York University. According to his LinkedIn page, he studied politics and Middle Eastern studies and volunteered on the Senate campaign of Hillary Rodham Clinton.
Diane Smulligan said her son was interested in government work, but had fallen on hard times following the death of his younger brother, Christopher, who was killed in a car accident in 2009.
"He had survivor's guilt," his mother said.
Months later, John Smulligan, who had moved to the Philadelphia area and worked in King of Prussia, was hit by a car and sustained serious injuries.
Her son, she said, had difficulty walking, which made it hard for him to find work.
In recent months, he stayed on and off at city-run shelters as he looked for a job as a waiter.
"He was trying to get a second chance," Diane Smulligan said.
Her son would have turned 31 this Friday.
Inquirer staff writer Michaella Bond contributed to this article.