Nesting is a form of preparing for mother hood by women bearing a child or by animals and birds, all getting ready to have a clean nest, ready for the birth. So let them do all the cleaning and preparing they want, while you rest.
Sure, it is okay if you ask if help is required, other than that, stay out-of-the-way . . .Especially if this nesting mother is dangerous or not, being human or animal. All pregnant things can be scary when it is nearing the end, the nesting stage.
Of course, this little learning lesson, is about some humans in their nesting stage. If they want to be on their hands and knees washing the floor . . .LET THEM. Asking, to do the floor washing for them, can be harmful, to your health.
If you know anyone nesting, just remember to offer them something to eat, instead of wanting to do their work. Sure ask if help is wanted, and nothing more.