Option (1) is incorrect: Uncle cannot be a guardian of an illegitimate child.
Option (2) is incorrect: Grandfather cannot be a guardian of an illegitimate child.
Option (3) is correct: Under Section 6 of the Hindu Minority and Guardianship Act, 1956, in case of an illegitimate boy or an illegitimate unmarried girl, the mother, and after her, the father can be the guardian.