Who raised Esther as his own daughter after her parents died?

Answer: Mordecai

Mordecai brought up Hadassah (Esther), the daughter of his uncle, and took her as his own daughter when her father and mother died.

“And Mordecai had brought up Hadassah (that is, Esther), the daughter of his uncle, because she did not have a father or mother. The young woman was lovely in form and appearance, and when her father and mother had died, Mordecai had taken her as his own daughter.”— Esther 2:7 (BSB)