VB Code:
'Connection string template.
Const CONNECTION_STRING As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};User Id=admin;Password=;"
'Get all MDB files in the folder.
Dim databaseFiles As String() = IO.Directory.GetFiles("folder path here", "*.mdb")
Dim connection As New OleDbConnection
For Each filePath As String In databaseFiles
'Substitute the actual file path in the template.
connection.ConnectionString = String.Format(CONNECTION_STRING, filePath)
'Connect to and manipulate your database here, then disconnect.
Next filePath