Code request to delete numbers in column B automatically

Hi,
Please suggest me a code to delete the serial number in column 'B' if the cell in column 'C' is blank or I deleted the value in column 'C'.

Private Sub Worksheet_Change(ByVal Target As Range)
'AutoSerialNumbers
    With Range("B6")
        .Value = "1"
        .AutoFill .Resize(Range("c" & Rows.Count).End(xlUp).Row - .Row + 1), 2
    End With
    MsgBox "Done!", 64
End Sub

In short if the cell in column 'C' is blank then there should not be a serial number in column 'B'. The code should run only when there is a value in column 'C' automatically. I want to insert this code in sheet module to run it automatically after theere is any change in column 'C'.

Any help will be appreciated.

Thanking you,