ASP.NET is a set of tools and libraries for building web applications on the .NET platform.
SignalR is a library for ASP.NET that simplifies real-time communication between server and client. You can host on a server yourself, or use the Azure SignalR Service for a fully managed platform.
ASP.NET MVC is a rich framework for building web apps and APIs using the Model-View-Controller design pattern. Use MVC to build data rich, dynamic websites with a clean separation of concerns.