According the Help section here:
http://helpcenter.admob.com/content/enabling-google-adsense-ads-your-applications
It says:
Can I filter or manage the AdSense ads that run in my application? Do
the existing filters I set for my application apply to AdSense ads?
No, at this time you are not able to apply any filters on the content
or type of AdSense ads that run inside your application.
We thought we might put in subliminal messages like "click more" or
"more clicks mean more happiness" - but I don't think AdMob will think
it is as funny as we do. It would be nice to know when AdMob expects
to have the filters start working for Adsense. Any word on that?
-Jim