Is it permissible for my elderly, blind grandmother to perform ablution (wudu') if she cannot tolerate ablution with cold water in winter?

The questioner should know that ablution (wudu') is a condition for the validity of prayer (salat), and one should not resort to dry ablution (tayammum) unless water is unavailable or one fears harm from its use. The high location of the ablution area and the wetting of clothes are not considered excuses. Rather, a basin of water can be brought for her to perform ablution while sitting. If she cannot find anyone to hand her the water, she may perform tayammum. As for winter, if cold water harms her, it is obligatory to heat it; otherwise, she may perform tayammum.