My father placed shares worth twenty dinars in one of the banks, and their value doubled to become five thousand dinars. When my father passed away, one of the scholars told us that it is permissible for us to take the money. What is the ruling on this money, considering that it comes from a bank and involves interest (Riba)?
Allah The Almighty Said (What means): "And if you repent, then for you is the principal of your wealth. You do not wrong, nor are you wronged." [Al-Baqarah/279]. This is the precautionary ruling regarding what you are asking about. You are entitled to the principal amount, and you should give the excess as charity to the poor and needy. If you are poor, you may take from it. And Allah The Almighty Knows Best.
What is the ruling o associations (Whereas a person who have money buys a commodity for a person and and gets a profit on it)?
It is permissible for a person to buy a commodity for someone's else and have a profit/loss on it
My mother is 70 years old and wishes to perform Hajj and Umrah, as she has never done so before. However, she also takes care of my ill father and is afraid of falling ill herself. What should she do?
If this is the obligatory Hajj – meaning she has not previously performed Hajj or Umrah – then it is permissible for her to go even without her husband's approval. However, she must travel with a Mahram (a male guardian) or a trustworthy group of women, and she should leave someone to care for her husband and attend to his needs. And Allah Knows Best.
We collect funds from mosques and other sources, saying: "For the poor, the needy, widows, orphans, and those who do not beg insistently." After paying the stipends of the families registered with the Zakat Committee, an amount exceeding 6,000 dinars remained. Is it permissible for me to save it for upcoming months when I may not be able to collect the stipends?
These funds are received by the committee as representatives of the zakat payers to deliver zakat to those entitled to it. It is well-known that delaying zakat while being able to pay it is not permissible. Imam Al-Nawawi (may Allah have mercy on him) said: "Zakat must be paid immediately if one is able to do so, by the presence of wealth and the eligible categories." [Al-Minhaj] Therefore, the committee must distribute the zakat to the eligible recipients without installment payments or using it to purchase material goods for them, as the committee does not have authority over the poor to allocate it in this way. And Allah Knows Best.