Old women are excused from the order of the Hijab. Allah Ta’ala says:
Translation:- And there is no sin on those elderly house confined women who have no desire (now) for marriage if they lay aside their garments (i.e. additional outer covering) provided they (too) do not show their adornment. And if they are (more) committed to self restraint (i.e. do not remove additional outer coverings as well) that is better for them. And Allah is All Hearing, All-knowing. Surah Noor-(24:60)