Both those names were common in Liudvinavas. Nearby towns are Bartninkai and Barzdai. I didn't see anything with a name closer to "Baniowski." Apparently there are no town names at all that begin with "Ban" http://lithuaniangenealogy.org/static_db/LT-settlements.php
Be aware also that illiterate people sometimes confuse B with P as they sound similar, especially at the beginning of a word.
There is a subdistrict of Vilnius that's named Deltuva. Sometimes people lived in or near the town or subdistrict after which they were named, but not always. If I were you I'd be betting on someplace near Liudvinavas since both surnames could be found there.
This page is a great resource for figuring out real names and where they originated: http://pavardes.lki.lt/ Use Google Translate and do a little experimentation to figure out how it works.
Also, type a surname into Facebook to find people with that name. Lithuania is a small country, and many people have left the rural areas in favor of cities, but if you check each person with the name you may find some from the area your relatives left.