public delegate string ConfirmTheClient(string foreignContext);
//...
public class MySvc
{
  public static string RetrieveContextData(string foreignContext)
  {
      // ...
  }
  public static void StartServer
  {
                       Type type = typeof(MyHub);
                        MethodInfo info = type.GetMethod(@"MyDelegate");
                        ConfirmTheClient cf = RetrieveContextData;
                        info.Invoke(null, new object[] { cf }); // <-------ERR
//Object of type 'NS1.ConfirmTheClient' cannot be converted to type 'System.Func`2[System.String,System.String]'
  }
}
public class MyHub : Hub
{
       public static void MyDelegate(Func<string, string> methodName)
        {
           //...
            return;
        }
}

                       Type type = typeof(MyHub);
                        MethodInfo info = type.GetMethod(@"MyDelegate");
                        Func<string,string> cf = RetrieveContextData;
                        info.Invoke(null, new object[] { cf });

        private Func<string, string> shadowDelegate;
        public static void ShadowDelegate(Func<string, string> methodName)
        {
            shadowDelegate = methodName; // <-err
            return;
        }
        public void SendMsg(string name, string message)
        {
            //shadowDelegate; <-----------------вызов
            return;
        }

        private static ConfirmTheClient cf = null;
        public static void ShadowDelegate(Func<string, string> methodName)
        {
           cf = new ConfirmTheClient(methodName);
            return;
        }