As I was working on one of the rails project which had calendar_helper plugin, which was not displaying year in the header of the calendar with month.
So I modified the calendar_helper.rb in the plugin lib directory.
Previously at line no.107 the code was
cal << %
("#{colspan}" class="#{options[:month_name_class]}">#{Date::MONTHNAMES[options[:month]]} )
just added #{options[:year]}
and modified it to
cal << %("#{colspan}" class="#{options[:month_name_class]}">#{Date::MONTHNAMES[options[:month]]} #{options[:year]})
Now month and year both displays perfectly in the calendar header