Ukranian and Hungarian on my mother's. My mother's side came from Galicia, White Russia and historical Hungarian territory which is now in Slovakia
You may be Carpatho-Rusyn on your mother's side. "White Russian" is a common way to refer to these people. Have you ever heard the term Lemko, Boyko or Hutsul used with regard to her? If so, she's certainly Carpatho-Rusyn. Galicia was full of them. For more info, start with c-rs.org and lemko.org.
Did they come in through Ellis Island? If so and you have not yet searched the Ellis Island records, do so. Try as many different spellings for your grandparents' names as you can think of. My grandfather's name was spelled differently in the old country, so it took a while to find it, but I eventually did.