Is my mother to feed a poor person for each day she missed fasting, or is the expiation waived for her inability to fast in the last two years due to her old age?

The elderly person who is incapable of fasting must feed a poor person for each day, based on the Almighty's saying: ﴿And upon those who are able to do it [but with difficulty] - a ransom [for abstaining] of feeding a poor person.﴾, and based on the saying of Ibn Abbas: "It is the elderly man and the elderly woman who are unable to fast, so they feed a poor person for each day." If the mother broke her fast due to old age and did not feed [the poor], then it is obligatory for the heirs to pay the fidyah from her estate.