My sister is divorced and her ex-husband, the father of her children, is her neighbor. He does not work and drinks alcohol even during the daytime in Ramadhaan. She refuses to give him money or food and some people blame her for that under the pretext that he is a sick person. Is it permissible for her to give him money in order to buy alcohol and food to eat and drink during the day in Ramadhaan?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger. 

A Muslim who excessively commits acts of disobedience and commits grave major sins should not be helped to do so. He should not be given charity or any other means. Rather, it is forbidden to give him charity as long as he uses it to disobey Allaah The Almighty, even if he is unable to earn his livelihood. This was clarified by the Shaafi‘i scholar, Abu Yahya Zakariyya Al-Ansaari .

This woman has done the right thing, because Muslims should give their charity to those who deserve it from among the righteous and religious people. Those who publicly disobey Allaah The Almighty are to be punished and deserted, not helped in their wickedness and disobedience.

Anyone who knows about the condition of this man is obligated to do his utmost in offering him advice and helping him to do righteous deeds. Furthermore, we advise his ex-wife to avoid letting her children sit or socialize with him in order to safeguard them from learning his bad habits.

As for the Sharee'ah-approved way to treat an immoral person,  please review Fatwas 20400, 22661 and 21837.

Allaah Knows best.