If the fair market value on the date of the gift was less than her cost basis you'll need that info. If more your basis is 1/2 her tax basis.
if FMV was less than her cost on the date of the gift you need to calculate as follows
if using cost produces a gain
but using FMV produces a loss
then you have either a taxable gain or loss.
if both produce a loss, that's not deductible.
