Is it permissible for a husband to leave his wife and child in their home and sleep at his widowed mother's house at night, knowing that his mother's house is unsuitable due to its age and the presence of insects, and his wife is not comfortable there?

There is no harm for the husband to stay overnight with his mother for a day or more, as long as there is no danger to his wife in that. The wife should not prevent him from doing so, as many scholars are of the opinion that the husband is not obligated to stay overnight with his wife except for one night out of four. It is advised that the wife be an aid to her husband in honoring his mother and that she should not let jealousy be a reason for him to fall short.