Is it permissible to fast on behalf of the dead who died owing missed fast to make up?
His relative should fast on his behalf, and it is permissible for the guardians to give permission to non-relatives of the dead to fast on his behalf as well. And Allah Knows Best.
Is it permissible for a teacher to have one of the school meals originally allocated to students considering that there is plenty of them and they may spoil?
All perfect praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
The Ministry of Education has the final say in this regard because it isn`t allowed to take from public funds save with the permission of the body in charge of spending from it. In fact, we have sent a letter to the Ministry concerning this issue and we are waiting for an answer. However, to prevent spoilage of the meals, they can be sold and the price kept in favor of the students or distributed amongst the students themselves. And Allah The Almighty Knows Best.
Is it permissible for the mother to give her children from the Zakah (obligatory charity) of her money?
It is permissible for the mother to give her children from the Zakah of her money if they are Zakah-eligible recipients, and she isn`t obliged to provide for them.
What should one who forgot to offer the second Sajda during congregational prayer, and remembered it before the end of the prayer do?
All perfect praise be to Allah, The Lord of The Worlds. Whoever forgets a pillar of prayer while in congregation must follow the lead of the Imam, and after the latter offers Tasleem, he should offer one Rakah, then perform Sujood As-Sahw (prostration of forgetfulness). And Allah Knows Best.