The word moulana has different meanings and usages in the Arabic language.
When it is used for Allah Ta’ala, it refers to guardian and protector.
When it is used for respectable people, it refers to leader or friend. It is reported in the Hadith that Rasulullah (Sallallahu Alayhi Wasallam) called Hazrat Zaid (Radiyallahu Anhu) by the title Moulana. Had this been exclusive to Allah Ta’ala, Rasulullah (Sallallahu Alayhi Wasallam) would not have called him by this title.
Hence, it is permissible to use the word Moulana for Ulama’ and respectable people of Deen.