This surname, spelled Radzevic^ius and pronounced rah-DZA-vi-chus, is relatively common (almost 200 listings in the online phone book for Lithuania just for the masculine ending "-ius", i.e., not counting women listed with the the ending "-iene" or "-ute"), so the odds of finding relatives without some information narrowing the search are not good.
The two villages named Babrai in the Lazdijai district each have a population under 100 (in 2001), so they are quite small settlements. The mobility of the population increased significantly under industrialization after WWI and later under Soviet rule (often forced). When you see the ending "-u" on a Lithuanian noun it means it is used in the possessive case, i.e., meaning "of or belonging to", as in the phrase "village of Babrai" = "Babru kaimas." It is customary in English to refer to such place and personal names with the nominative ending "-ai".
The ending of the surname is Urbanavic^us is spelled without any "r" in it. It is a common Lithuanian ending "-vic^ius" to many surnames.