आपसे is grammatically correct, right? I know there are other things wrong with option 1, I'm asking this only.
Yes. आपसे is correct.
Why तुझसे and not तुमसे
Intimate/very informal "tu" form versus informal (but not intimate) "tum" form. Both could be correct
Can we use unhe also?
Unhe is 'to them'. It doesn't really fit here.