Have her pack some toilet seat covers ( I get some from the local drug store or at the airports) and some hand sanitizer or wet-cloths. Other than taking sanitary precautions, there isn't much else she can do to avoid the situation. It's mind over matter.
Edited by: travelmaven
Rick Steves has a recent article about finding and using toilets in Europe, but it also applies to areas outside of Europe: http://seattletimes.nwsource.com/html/ricksteveseurope/2013729871_websteves21.html
My biggest beef about European toilets is that most of them require negotiating a steep staircase. When a knee problem makes negotiating stairs both slow and painful, this is simply not good enough. I rejoiced in a European tourist-oriented village when I found a diabled loo for a fellow-traveller whose knees are bad enough that she requires a wheely-walker, and can't even negotiate stairs painfully.
