My mother is 85 years old, and she has an issue related to urination; she cant control it even during Salah. She always washes her clothing and wears a clean piece of clothing and then offers her prayer. However, sometimes its become difficult for her.
what is the ruling In Islam on this specific issue?

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.

If your mother's condition is as you have described, then she is among those who possess a valid excuse, and thus she may perform wuḍūʾ after the time [of prayer] has entered, wear a pad or diaper [to guard against further impurity], and pray with that wuḍūʾ the obligatory prayer as well as whatever supererogatory prayers (nawāfil) she wishes — just as one afflicted with urinary incontinence or a similar condition would do.

According to the Mālikīs, she is not obligated to wear a pad or diaper, nor is she harmed by the impurity that emerges from her, and nor is she obligated to perform wuḍūʾ* [anew] after the time has entered either. She may adopt the concession of the Mālikī position if she has need of it and the position of the majority proves difficult for her.

Allah knows best.