If zwave will reach, there are lots of battery - controlled buttons you can use. 
see the Buttons FAQ. Some of the devices there are battery-operated, some are mains power, so read carefully. Most posts have a link to a discussion thread about that device.
If you have any questions about a specific device, please post them in the discussion thread for that device or come back here and ask them. Don’t ask in the FAQ. We try to keep it to just one or two posts for each device or it becomes too hard to use. Thanks!
FAQ: Full list of buttons and remotes confirmed to work with SmartThings
As far as the widget, since she has an android phone, as @Matt_Behnken suggested, SharpTools has an excellent widget feature for those. Unlike many other options, it has a toggle feature, so you can use the same widget for both on and off. It does have a license fee, but most people find it well worth it.
The developer, @joshua_lyon , is very active in this forum if you have any questions.