No information from any past census of the population is available due to privacy laws, except for the Austro-Hungarian censuses (1828, 1869) and earlier population and tax lists.
The church vital records of the Serbian Orthodox Church for the surnames you are researching exist. You need to contact the state historical archives and municipal offices, as well as the church because the original vital records have been returned to them last year.
Serbian genealogy Society SGS "Rodoslovlje"
http://www.rodoslovlje.com/en