'अपने गाँव' is in the oblique case because there is an implicit postposition between गाँव and जायेगा, corresponding to the preposition 'to' in the English sentence. In the oblique case, 'अपना गाँव' becomes 'अपने गाँव' .

The postposition is necessary (though not expressed here) because जाना is an intransitive verb and cannot take a direct object.