Help with Compiling Excel Spreadsheet Data into One Table

Hi everyone, having trouble with one line of code. I think I'm pretty close to figuring out this macro. I'm getting the following error:
"Run-time error '438':
Object doesn't support this property or method"
on this line of code: wbMstr.wsMstr.Range("c1").End(xlDown).Offset(1, 0).Select

How can I better define my method? Thanks!

Sub ImportCSVsWithReference()

'Summary:   Import all CSV files from a folder into a single sheet
'           adding a field in column A listing the CSV filenames

Dim wbCSV   As Workbook
Dim wbMstr  As Workbook:    Set wbMstr = ThisWorkbook
Dim wsMstr  As Worksheet:   Set wsMstr = ThisWorkbook.Sheets("Sheet1")
Dim fPath   As String:      fPath = "C:\Users\Eddie\Dropbox\Admob pull Data\Admob pull Data(eddie)\8.17\"    'path to CSV files, include the final \
Dim fCSV    As String

'If MsgBox("Clear the existing MasterCSV sheet before importing?", vbYesNo, "Clear?") _
    '= vbYes Then wsMstr.UsedRange.Clear

Application.ScreenUpdating = True  'speed up macro

fCSV = Dir(fPath & "*.csv")         'start the CSV file listing

    Do While Len(fCSV) > 0
      'open a CSV file
        Set wbCSV = Workbooks.Open(fPath & fCSV)
        wbCSV.ActiveSheet.Range(Range("a3:h3"), Range("a3").End(xlDown)).Copy
        wbMstr.wsMstr.Range("c1").End(xlDown).Offset(1, 0).Select
        
        wbCSV.Close False
      'ready next CSV
        fCSV = Dir
    Loop
 
Application.ScreenUpdating = True
End Sub