Menu in iPad and Android devices

The menu items are not showing up at all in three different mobile devices (iPad, iPhone, Samsung Galaxy, but showing up in Samsung Tab); the drop down icon doesn’t work at all, either. Website is peaceadvocacynetwork.org . One site visitor reported that the menu wasn’t showing up at all in two of her computer browsers (I checked in same browsers, same versions, and they were fine, so not sure what the deal is). Thanks for any help!