After speaking with Apple Support at length in Dec., we determined in was not the IOS Calendar but rather my Google calendar. Google has since fixed this issue, as evident in my recent dates not having any GMT listing in my IOS Calendar. But still, my older dates all had the GMT time. I stumbled on a solution, other than going into each date and editing all.
FIrst, make sure your Google calendar is synced. Then go to you iPhone or iPad's Setting-->Mail, Contacts, Calendars. There unders Calendars, scroll down to "Sync." Most people will have it set to "All Events," but change it to say "Events 2 Weeks Back." Check your IOS Calendar -- yes, it will show only 2-weeks worth of events, but the GMT listing will be gone. Then go back into Settings--> Mail Contacts, Calendars and changed the "Sync" to say "Events 3 Months Back." Keep checking your IOS Calendar and then changing your "Sync" until you have Sync "All Events." All the GMT references should be gone.
I Do hope this helps. I was so relieved to finally have my IOS Calendar back to normal.