Should I learn MEAN stack or else continue with PHP as backend development?

I have learnt lot of Javascript and I am still learning it(Never Ending Process). Also I learnt PHP as backend since I knew WordPress. So please all suggest me what should I learn? Should I learn

1) MEAN Stack or 2) Build Hybrid apps for Android & IOS with current knowledge or 3) move with PHP based web apps.

All developers are most welcome to suggest and advice. Thanks in advance :-)