My name is abubakar khan, and I am nisab holder, I pay zakat yearly,but last month my elder brother expired leaving behind his widow and small son 5 years old, with no permanent income to cope up with the necesseties of life.though I have elder brothers but I don't hope that they would this lady to get a permanent source of income. My question is that can I give my zakat amount to my elder brothers wife and without informing her that this is zakat money.I have been helping her during the last month by cash, but I want this money to go to her. Is it permissible?

Yes, it is permissible. You can do that.