It's not clear what you mean by "2 control buttons on the
menu page", but I will assume that you mean buttons on a
form.

The usual approach for this kind of thing is to add a text
box (named txtArea) to the form for users to enter the W,C,E
or nothing (for All).  Then a single button can do what you
want using code like this in its Click event:

Dim strWhere As String
If Not IsNull(Me.txtArea) Then
    strWhere = "[Service Area] = """ & txtArea & """"
End If
DoCmd.OpenReport "yourreport", acviewPreview, _
        WhereCondition:= strWhere

the easiest way to do this is in the form, not the report. add code to the
"All" button's Click event procedure, to simply open the report (with no
criteria in the underlying query), as

   DoCmd.OpenReport "ReportName"

on the "Specific area" button, you can add code to get the area input from
the user and then open the report with a WHERE clause applied, as

   Dim strArea As String
   strArea = InputBox("Enter the area.")

   DoCmd.OpenReport "ReportName", , , "AreaFieldName = '" _
       & strArea & "'"

or preferably, you could use the button to open a form with a combo box on
it, that has the areas listed in the droplist, so the user can't enter an
invalid area; just add a command button to the form to run the OpenReport
action after a value is entered in the combo box.

or, easier yet, just add a combo box to your menu form, so the user can
select the area. in this case you could actually use one button to open the
report, rather than two - with the following code, as

   If IsNull(Me!cboArea) Then
       DoCmd.OpenReport "ReportName"
   Else
       DoCmd.OpenReport "ReportName", , , "AreaFieldName = '" _
           & Me!cboArea & "'"
   End If

hth