There are 2 methods that I know can be used to insert ads into wordpress Jetpack mobile theme.
1. Hacking the code
Use Chrome developer tools on your browser. Switch it to mobile screen (icon on top right). Browse to your wordpress site. Now the mobile version is presented. Right click, then view page source. Find the string “id=’style-css'”. Notice in the href it will show your mobile theme files. Now download those files, and find content or page file. You can insert your ads in that file.
2. Using WP Plugin
The easiest way is to install a plugin called Mobile Theme Ads for Jetpack. On your dashboard, go to plugins and add new. Search for this plugin, install and activate. Then in Settings, configure the plugin then save.