Oh so she's on a PC (not a Mac)?
In that case, I think you'll have to have some intermediate software. If you have Outlook, you can try syncing the Google calendar to that (
using 1-way sync), then syncing that to MobileMe, then stop syncing to the Google Calendar.
If you don't have Outlook, there are a few pieces of software that might help you, but I'm not sure what they're called or how they work. Trying doing a web search.