Protected _parentModule As DotNetNuke.Entities.Modules.PortalModuleBase

 

_parentModule = CType(FindModuleInstance(Me), DotNetNuke.Entities.Modules.PortalModuleBase)

 

 Public Shared Function FindModuleInstance(ByVal fCtl As System.Web.UI.Control) As System.Web.UI.Control
            Dim ctl As System.Web.UI.Control = fCtl.Parent
            Dim selectedCtl As System.Web.UI.Control = Nothing
            While Not ctl Is Nothing
                If TypeOf ctl Is DotNetNuke.Entities.Modules.PortalModuleBase Then
                    If CType(ctl, DotNetNuke.Entities.Modules.PortalModuleBase).TabModuleId = DotNetNuke.Common.Utilities.Null.NullInteger Then
                        If selectedCtl Is Nothing Then
                            selectedCtl = ctl
                        End If
                    Else
                        selectedCtl = ctl
                        Exit While
                    End If
                    Exit While
                End If
                ctl = ctl.Parent
            End While
            Return selectedCtl
        End Function

 

After you get the parent module you can get the ID by _parentModule.ModuleId