Still not clear what you want but if c is meant to represent the column that is to be averaged I would write it something like this.
Dim rng As Range

    Set rng = Sheets("Series Formatted Data").Cells(1, 1)

    Do While rng.Value <> ""
       Select Case rng.Value
           Case "MobileReceivePower"
                   Sheets("Sheet1").Cells(1, rng.Column).Formula = "=Average('Series Formatted Data'!" & rng.EntireColumn.Address & ")"
           Case "Best_EcIo_Active_Set_0"
                   Sheets("Sheet1").Cells(1, rng.Column).Formula = "=Average('Series Formatted Data'!" & rng.EntireColumn.Address & ")"
           Case "MobileTransmitPower"
                   Sheets("Sheet1").Cells(1, rng.Column).Formula = "=Average('Series Formatted Data'!" & rng.EntireColumn.Address & ")"

      End Select
      Set rng = rng.Offset(, 1)
      
   Loop
PS Images don't really help.