Is it permissible for a mother to move from her town to complete her 'iddah in another city under the care of her daughter, due to her old age and illness, and her need for healthcare not available in her town?

The best righteousness towards parents is to supplicate for them, whether they are alive or deceased, as Allah Almighty says: "And lower to them the wing of humility out of mercy and say, 'My Lord, have mercy upon them as they raised me when I was small.'" There is no harm in the mother moving to live with her children in the city if her remaining in her small hometown causes her harm.