There is a ticking time bomb here- lenders have been sending warning notices for a while but I think many people either haven't read them or understood them or, more likely, have just put the problem off to another day.
How long ago was the mortgage taken out. Interest only mortgages used to be endowment ones with an associated life policy, although for many the payout will not be sufficient to cover all the capital sum. Does she have any policies at all?
She could consider equity release or simply extend the mortgage.
Or she could sell up ad move to a cheaper property.
It'll be interesting to see how lenders deal with people who can't pay, especially if they are pensioners