What should we do about the failure to return money and books lent to some brothers who live on aid, especially since my husband finds it difficult to ask for them back, and I do not like that either?

A حسن (goodly) loan is one of the best acts of devotion. There is no blame on the husband if he refrains from lending money to someone who does not keep trusts and procrastinates in repayment. However, if the borrower is in straitened circumstances, it is better to grant him a respite and be gentle with him. The husband has the right to demand his money with gentleness and kindness. The debtor must repay the debt. "Whoever takes people's money with the intention of repaying it, Allah will repay it on his behalf, and whoever takes it with the intention of destroying it, Allah will destroy him." Nothing is lost with Allah, and the spouses will be compensated on the Day of Resurrection with good deeds for what they lost in this world.