It depends which timeshare company she's with - and those maintenance fees are fairly standard each year.
The one we're with won't buy them back routinely, but would do so under certain circumstances - really, she needs to get in touch with them a.s.a.p. and ask for leniency and whether, under the circumstances, she could surrender her ownership. She needs to emphasise her age and her reasons for no longer needing it.
One company I was with just let us surrender the timeshare week - another says I need to sell it, so I've got it for sale with a timeshare resale agency. However - I only know about my ownership, other timeshare companies may have different policies.
Does she have any family or friends who could buy the timeshare week from her, and use it? You're allowed (with mine) to do that, but the new owners do have to take on the maintenance fees etc.