I have such great love for my mother that I want to do charitable deeds and dedicate their reward to her after her death. Is it better to fast one month every year and dedicate its reward to her, or to feed thirty poor people for that month and dedicate the reward to her? Is it necessary to feed thirty individual people, or may I distribute the food among the greatest possible number of families? Is it permissible to specify a sum of money to give in charity and dedicate its reward to my mother? And what is the nisab (the minimum amount of money on which zakat is due) on wealth?

All the charitable deeds you want to perform are permissible. It is established in Islamic law that an act whose benefit extends to others is more beneficial and more earns one a greater reward than an act whose benefit is limited to the person who performs it. If you are able to either feed the poor or fast, the better choice is to feed the poor because it is a good deed whose benefit extends to others.

As for zakat on wealth, it is the value of 85 grams of 21-carat gold at the market price, payable when zakat becomes due upon completion of one lunar year.

And Allah Almighty knows best.