Pamela Becker, whose brother is the mayor of Salt Lake City, met Nicholas DeTommaso in the 1990s, the New York Post reported.
She befriended him and, by 2002, had moved into his two-bedroom, $100-per-month apartment.
In 2006, DeTomasso was diagnosed with dementia, and Becker received his power of attorney in 2007.
DeTomasso then adopted Becker in 2009, and she became the beneficiary of his life insurance and pension benefits, the Post said.
After DeTomasso died, Becker continued to live in the apartment despite the owners' repeated attempts to evict her.
Last month, the state Division of Housing and Community Renewal ruled Becker was not entitled to the apartment because she lived as a family member in the apartment for only 22 days before DeTommaso's death.
But Becker, who denies that DeTomasso was senile, said she intends to fight that ruling.
"I'm legally adopted," she said. "I'm going to win this battle."