I'm making taxes but do I put my mom and sister as dependents?

Unless you are the main support for the family, no, and maybe not even if you are. How old are you? How old is your sis? How much did each of the three of you make?

How much money did mom make?
If she made more than $3950, she is not your dependent.

To claim your sister as YOUR dependent, your income must be more than your mother's as well as meet other tests.

As for their W-2s, if their income is very low and they want to file to get a refund of income taxes withheld, they file. If they are your dependents, they check that box on the 1040EZ.

If your mom made over $3950, no. Same for sister, possible you could claim her if she is under 19 or under 24 and a full time student AND you provided over 50% of her support.