Best remote database for Android app

I am developing a android application for my family members just like a social networking site.But i don't know any proper database to be used as remote back end.Also I need a database which serves the post's based on timestamps.Also my database should be flexible of inserting any type of files(txt,png,PDF etc...) for downloading by the user's.Suggest a goodbase One more thing I recently used MongoDB an I am fed up using the java driver for the accessing of data in Mongo DB.Is MongoDB also a good option of selecting asa remote database.Also suggest me the links for installation also.