Mom (91) is incontinent. I have changed bedding and cleaned her room but it always smells like urine. How can I eliminate smell?

Possibly the bed is saturated from previous accidents. Consider replacing it and using a waterproof mattress encasement (has a zipper, covers the whole mattress. May need to do linens and bedclothes daily, first thing in the morning. Good idea to use dog urine destroying chemicals. Consider an exhaust fan blowing air out of the room (create negative pressure environment) depending on your weather conditions. Use scents designed to cover up nursing home smells. My Mom does the exact same thing, saturates the bed at night. Difficult.

My dad has dementia, he pees on the floor near commode. I use dog training pee spray to get rid of the smell.

Remove all coverings and stick your nose in the mattress pad. Maybe you didn't start protecting it soon enough.

Sounds like you're doing a great job of keeping things clean so can't understand the urine smell. Does your Mom use any topical products like muscle rubs for aches and pains? Usually these contain menthol in them. The reason I ask is that years ago before my folks moved in with me I went to visit them and their whole house smelled like old urine. Neither of them were having trouble with incontinence. What I discovered was that Mom was using an OTC muscle rub for aches and pains. That muscle rub when it had been on for a long time developed a smell just like old urine. Needless to say she stopped the muscle rub and the smell went away. Just a thought. Hope you find the source of the problem.