How to show Year with month name in monthview control

You should handle BeforeCellRender event and change e.HeaderText.

See an example from Demo/Month/CustomRendering.aspx.cs (visible as www.daypilot.org/demo/Month/CustomRendering.aspx). This example sets the cell header font to bold by wrapping it inside <span> element.

protected void DayPilotMonth1_BeforeCellRender(object sender, 
  DayPilot.Web.Ui.Events.Month.BeforeCellRenderEventArgs e)
{
  if (e.Start == DateTime.Today)
  {
    e.HeaderText = String.Format("<span style='font-weight:bold'>{0}</span>", e.Start.Day);
    e.HeaderBackColor = "#FFD3BD";
  }
}

For showing day + month + year, you can use something like this:

e.HeaderText = String.Format("{0:d MMMM yyyy}", e.Start);