His mother died owing the fasts of two Ramadans
Question

My mother has died, and she told me when she was still alive that she owed the fasts of two months, Ramadan in two years, when the month of fasting came when she gave birth. When she died, she had not made up these fasts. Should I fast on her behalf or feed the poor? How is feeding the poor to be done? Should I slaughter some goats and share it out among sixty households, or should I give the value of the food in money?.
Praise be to Allah.The best thing to do is to fast on behalf of your mother, because the Prophet (blessings and peace of Allah be upon him) said: “Whoever dies owing any fasts, his next of kin should fast on his behalf.” Saheeh -- agreed upon. The next of kin is the relative. But if you or any other relatives cannot fast, then feed the poor from her estate or from your wealth, one poor person for each day. The amount to be given is half a saa‘ of the local staple food. If you do it all in one go and give it to one poor person, that is also acceptable. 
And Allah is the source of strength. May Allah send blessings and peace upon our Prophet Muhammad and his family and Companions. End quote. 
Standing Committee for Academic Research and Issuing Fatwas