If you created the page for your grandmother you should be able to make changes to it.
You must be in edit mode in order to change the information. Select one of the small  buttons on the profile page, make your desired changes and be sure to press the grey "Save Changes" box about half way down the page.
If you did not create the page then you must "request to join the trusted list". This option is found at the top of the page under "COMMENTS"