Если ячейка пуста - значение предыдущего столбца в список C

Sub asdf()
Dim mrng As Range, cC As Range, i&, mARR()
   i = Cells(Rows.Count, 1).End(xlUp).Row
   Set mrng = Range(Cells(1, 2), Cells(i, 2)).SpecialCells(xlCellTypeBlanks)
   ReDim mARR(1 To mrng.Cells.Count): i = 0
      For Each cC In mrng
         i = i + 1: mARR(i) = cC.Offset(0, -1).Value
      Next ' cC
   [c1].Resize(UBound(mARR), 1).Value = Application.Transpose(mARR)
End Sub

Dim mrng As Range, cC As Range, i&, mARR()
   i = Cells(Rows.Count, "A").End(xlUp).Row
   Set mrng = Range([b1], Cells(i, "b")).SpecialCells(xlCellTypeBlanks)
   ReDim mARR(1 To mrng.Cells.Count): i = 0
      For Each cC In mrng
         i = i + 1: mARR(i) = cC.Offset(0, -1).Value
      Next ' cC
   [c1].Resize(UBound(mARR), 1).Value = Application.Transpose(mARR)

Sub asdf()
Dim mrng As Range, cC As Range, i&, mARR()
   i = Cells(Rows.Count, "A").End(xlUp).Row
   On Error Resume Next ' start error handling
   Err.Number = 0
   Set mrng = Range([b1], Cells(i, "b")).SpecialCells(xlCellTypeBlanks)
   If Err.Number > 0 Then MsgBox "NOT FOUND BLANKS": Exit Sub
   On Error GoTo 0 ' end error handling
   ReDim mARR(1 To mrng.Cells.Count): i = 0
      For Each cC In mrng
         i = i + 1: mARR(i) = cC.Offset(0, -1).Value
      Next ' cC
   [c1].Resize(UBound(mARR), 1).Value = Application.Transpose(mARR)
End Sub

   ReDim mARR(1 To mRNG.Cells.Count, 1 To 1): i = 0
      For Each cC In mRNG
         i = i + 1: mARR(i, 1) = cC.Offset(0, -1).Value
      Next ' cC
   [c1].Resize(UBound(mARR,1), ubound(marr,2)).Value = mARR
 End Sub