The absolute simplest thing I can think of is to simply build a table with a border and enter the details in each block. That should be a piece of cake. Set it up with appropriate rows and columns. You could even nest another table within each block(to organize and configure the way the date, the details, etc look). Of course the dates and info would have to be manually configured, but it would certainly be simple to do.
Set up a large text block at the top for the Month/Year. Then the table. In the top row, list the days of the week. Then in each cell of the calendar nest another table with 2 rows. One for the Date (set it in bold and justified left or right) and the second for the day's events. They can be linked and manipulated like any other text.
This isn't a fancy or auto-configured solution...but it will certainly do the trick.
You can, of course, build different versions for whatever day of the week the month starts on then delete the extra days as needed...and each month just give her a "template" to drop data into. I'd set up a Calendar page with links to each month for a couple years...then just have her drop in the events and build the links...
I know this is simplistic, but any user should be able to handle working with this once the original table is made. If you want a hand with the table itself, let me know.
Hope this helps!
