Is it considered a sin to disobey one's husband and bring a cat into the house to entertain the children during his absence, knowing that he dislikes cats, but the cat will be returned after the lockdown ends and he will not be affected by its presence?

You should refrain from bringing the cat into the house to avoid the consequences of the husband's anger, because obedience to the husband is obligatory in matters that do not involve disobedience (to Allah), and it takes precedence over obedience to parents. Also, the children's free time should be filled with activities that benefit them religiously and worldly to avoid boredom, for childhood is a fertile stage for teaching children and instilling goodness in their souls. A child is a trust given to his parents; if he is accustomed to goodness, he will be happy in this world and the hereafter, and if he is neglected, he will suffer and perish. It is the parents' duty to protect their children from the fire of the hereafter by disciplining them, teaching them noble manners, and safeguarding them from bad companions.