Your answer, "Heli", is not correct.
The correct answer to
Who is Joseph's father (i.e. Jesus's grandfather)?
is
Jacob
as shown by
Matthew 1:16
which is
- KJV
- And Jacob begat Joseph the husband of Mary, of whom was born Jesus, who is called Christ.
- NIV
- and Jacob the father of Joseph, the husband of Mary, of whom was born Jesus, who is called Christ.