business processes Framework (Xamarin or ReactJS)

maybe someone can help me. In near future i'm going to develop a business processes application like this :

https://play.google.com/store/apps/details?id=de.semture.cubetto

https://play.google.com/store/apps/details?id=com.showgen.processcraft

Now i would like to know if there are some already existing Frameworks or projects for that. I just want play arount with that subject to get a feeling how it works and what i have to do. I'm planing to make it available for Android (highest priority) and Web (Ios and windows arent so important right now).

So my first question is. Are there any Frameworks, libs, project availbe for something like that?

I've already searched for some frameworks but without no success...

And the other question would be what Tool or language should i use ?

Currently i'm working with Visual Studios 2015 Xamarin (xml & C# based language). We all know that i can make crossplattform apps with xamarin. But some minutes ago i've heard that there is a language/Framework named React.JS, that is also for android ios and web apps.

Now my second question:

which one should i work with ? Xamarin or React.Js ? Which one would better fit to my project and what are the main differences ?

I hope someone could answer that :)

Thanks in advance