Superiority of fasting Mondays and Thursdays to fasting al-Ayyaam al-Beed
Question

My mother for a long time has regularly fasted on Thursday and Monday of every week, but now she wants to ask and find out whether this action is better or should she fast three days of every month?.
Praise be to Allah.This action is better and brings a greater reward, and fasting three days (of every month) is included in that. The Prophet (blessings and peace of Allah be upon him) used to fast on Mondays and Thursdays, and he used to say: “They are two days on which deeds are shown to Allah, may He be glorified, and I would like my deeds to be shown (to Him) when I am fasting.” and Allah is the source of strength. End quote. 
Shaykh ‘Abd al-‘Azeez ibn Baz (may Allah have mercy on him).