What is the ruling on money that a grandmother received as Zakat, then lent out, knowing that she did not pay Zakat on it under the pretext that it was Zakat money, and is it sufficient to give charity with an intention other than Zakat for past years?

If the grandmother is in need due to her daughter's insufficient financial support, or because her provider is her daughter's husband who is not obligated to support her, then she may receive zakat. If the amount she received from zakat reaches the nisab and a hawl (full lunar year) passes over it, then zakat becomes obligatory on it. Since zakat does not lapse with the passage of time, she must estimate the years in which the money reached the nisab, and then pay two and a half percent for each year that passed while it was at nisab. If her daughter's husband, who borrowed the money, is wealthy and not a procrastinator, then she owes zakat on the borrowed money. However, if he is a procrastinator, she should wait until he repays it to her, then pay zakat on the money for one year if it remained in his possession for one year or more. The nisab for Riyal is equivalent to 85 grams of gold or 595 grams of silver, and the amount due is 2.5%.