Creating a mobile application. Only a simple calendar with some features. Should I use native code or use hybrid?

I know java and HTML , CSS and JavaScript. Question is which one would give me the least headaches?

What about nativescript? You write javascript and it compiles to truly native code (ios & android at the same time). But truly native means (as far as i read it) that they use true native ui components but they run javascript in the background (like hybrid apps, but have better performance, since not wrapped into a webview ..) pls correct me if i am not informed correctly (also sry for my bad english)

Yeah nativescript and meteor.js for the backend.

I have used the Ionic framework before. With the Cordova features. Not phonegap.

i think React Native is the right choice for you
ReactJS + iOS/Android native UI
the business logic will be shared but you have to specify the UI components per each platform