Is it permissible for an elderly, blind woman, who has no one to guide her to the bathroom for ablution, to perform Tayammum for Qiyam al-Layl?

A woman is not permitted to perform tayammum unless she has exerted her effort to find water and has not found it. For example, she should seek someone to place water near her so she can perform wudu' in a vessel outside the bathroom. If she is unable to obtain water by any means, then she is permitted to perform tayammum, based on the Almighty's saying: "And if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and find no water, then seek clean earth and wipe over your faces and your hands [with it]. Indeed, Allah is ever Pardoning and Forgiving." The preponderant opinion is the permissibility of tayammum for supererogatory (nafila) prayers when its cause is present.