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 is His slave and Messenger.
If the money which you possess, either gold or silver, cash money or tradable items reaches the Nisaab (minimum amount liable for Zakat) and a whole lunar year elapses on it, then it is an obligation to pay Zakat on it, even if the money belongs to a widow or an orphan that is invested. For more benefit, please refer to Fatwa 93584.
As regards the reward for cultivating your children, you should know that if a woman nurtures her children well, then she will have the reward of sponsoring orphans as the Prophet said: “The person who sponsors his own orphans or other people's orphans, I will be in Paradise with him like this: and he pointed putting his index and middle fingers together."
It is also confirmed that the Prophet said: “I will be the first one to whom the door of Paradise would open, but a woman will rush towards me, I would ask her: “What is the matter with you? Who are you?” She would respond: “I am a woman who dedicated herself to taking care of my orphan children.” [Abu Ya'la]
The Prophet also said: “I and a woman with some blackness on her cheeks [due to hardships and difficult life] will be in paradise like this, [pointing with his index and middle fingers] a woman who became a widow and she restrained herself to their nurturing until they grew old or died (and did not get married).” [Ahmad and Abu Daawood]
Therefore, glad tidings to you of a great reward from Allaah and we ask Allaah to reunite you with your husband in Paradise.
For more benefit on a woman who will be with her husband in Paradise, please refer to Fatwa 83305.