A       B        C        D        E        F
1 С1	С2	С3	С4	С5	С6

Sub X()
    Dim rng As Range
    Dim avarData As Variant
    Dim avarNew() As Variant
    Dim intI As Integer
    Dim intJ As Integer
    Dim intMin As Integer
    Dim intMax As Integer
    Dim intPos As Integer
    Dim strLetter As String
    
    Set rng = Range("A1")
    avarData = Split(rng, ",")
    ReDim avarNew( 0 )
    
    For intI = LBound(avarData) To UBound(avarData)
        intPos = InStr(LTrim(avarData(intI)), "-")
        If intPos >  0  Then
            Y LTrim(avarData(intI)), intPos, intMin, intMax, strLetter
            For intJ = intMin To intMax
                avarNew(UBound(avarNew)) = strLetter & intJ
                Debug.Print strLetter & intJ
                Z avarNew
            Next intJ
        Else
            avarNew(UBound(avarNew)) = LTrim(avarData(intI))
            Debug.Print LTrim(avarData(intI))
            Z avarNew
        End If
        
    Next intI
    
    For intI = LBound(avarNew) To UBound(avarNew)
        Range("A" & intI +  1 ) = avarNew(intI)
    Next intI
End Sub

Sub Y( _
  ByRef strTemp As String, _
  ByVal intPos As Integer, _
  ByRef intMin As Integer, _
  ByRef intMax As Integer, _
  ByRef strLetter As String)
    Dim intI As Integer
    Dim strL As String *  1 
    Dim strT As String
    
    intMax = CInt(Mid(strTemp, intPos +  1 ))
    
    For intI = intPos -  1  To  0  Step - 1 
        strL = Mid$(strTemp, intI,  1 )
        If IsNumeric(strL) Then
            strT = strT & strL
        Else
            intMin = CInt(strT)
            strLetter = strL
            Exit For
        End If
    Next intI
End Sub

Sub Z(ByRef avarArray() As Variant)
    ReDim Preserve avarArray(UBound(avarArray) +  1 )
End Sub

A1 = "С1, С2, С3-6"

A1 = "C1"
A2 = "C2"
A3 = "C3"
...
A6 = "C6"