A B

I use Socket.IO because this enables real-time, bidirectional and event-based communication between the browser and the server.

It's simple to use and to implement over an application, once used on the backend it is like a symbiosis between and across all your application.

I use Vue.js because the simplicity, versatility and effectiveness that provides for building an SPA application as well as the one binding, combined with the lifecycle. It uses the MVVM architecture. The state management with mutations make it reactive and powerful for instant almost real time data management. JSX is also available for functional components that provides on performance for a simple or complex application.