The word нђдо is an o-form predicate word, and, like most o-forms (cf. Мнљ скџчно), is used with the Dative.
Мнљ (Dat.) нђдо встрљтить своегћ дрџга. I have to meet friend of mine.
Although you may hear people use нђдо with nouns (e.g. Мнљ нђдо рџчку), you should avoid this colloquial usage and reserve нђдо for constructions with infintives. Use нџжен, нужнђ, нџжно, and нужнІ with nouns, and make sure the form that you use agrees with the noun (e.g. Мнљ нужнІ рџчки).