Have tried everything to fix iCal duplicate entries

That's probably the problem. When you try to replace the calendar on your phone with the calendar on your Mac it isn't transferring over because your phone isn't syncing any more.

When you connect your phone, does it appear on the left side of iTunes under Devices?

On your phone, when you go to Settings>Mail,Contacts,Calendars...scroll down to the Calendars section and tap Default Calendar is your From My Mac calendar selected rather than the calendar under On My iPhone or something else?

Also, are you able to sync other data with iTunes such as your music and apps? i.e., is this just a problem syncing your calendar?

What is selected under Default Calendar?

You're welcome. At this point I would suggest you make an appointment with the genius bar at a nearby Apple store and take both your phone and, if possible, your computer with you to have them take a look at what's going on. It may be a setting in iTunes or on your phone, or they may need to reset your SyncServices folder (http://support.apple.com/kb/TS1627) to get your calendar to sync properly. Once you re-establish calendar syncing you'll be able to replace the calendar on your phone. Good luck!

Contacts & Calendars does not work on or iCloud... The problems with dublicating contacts & calendars was originated on Mobile Me... When they changed Mobile Me to iCloud with alot of fanfare, they failded to fix these issues.... I joined iCloud expecting a new world... Jobs saying "It just works" clearly never used it himself... It is a disaster... I have numerous hours redoing my calendars and contacts.... The only safe way to get Calendars and Contacts is when you sync your iphone or ipad on your mac, go to itunes, click on your iphone, go to the section called Info, scroll down to Advanced, click on Contacts and Calendars, this will remove and replace your contacts & calenders safely.

She's tried to replace her calendar as you are suggesting multiple times without success. She also isn't syncing with iCloud.

Don't feel bad. I have this happen 3/4 of the time I upgrade my phone s/w. I have been using a IPhone since I replaced my treo. I like the phone but their calendar support stinks. I have had entries occur in duplicate, triplicate and I even had a set of entries replicate 10 times. Most of the time if I force my Mac to replace the IPhone calendar if fixes most of the problems but very often not all of the problems. Apple has a problem and they just do not seem to get it right. A couple of years ago, the switch to DST caused me grief so I never look forward to DST/EDT changes. I have opened multiple enteries on the community but to no avail. Good luck.