Please give me advice. How to get rid of odor??

My first thought was that the odor has a physiologic cause, not just hygiene. Interesting article in the Daily Mail on a study that does that to be true. It also found that antioxidants reduced the smell. Here's a shortcut url to it: bit.ly/3dN2ejw

Try borax or an enzyme cleaner for the laundry. There's also a Huffington Post article on products developed in Japan to address this challenge. bit.ly/3es3d7W

It may be her meds. And the elderly do have a certain smell. There is a reason for it. Look up "old people smell". It will explain the cause. I think deodorant soap is suggested. Maybe rinse her hair with vinegar. Wash everything she brought with her with vinegar in the rinse cycle. Then hang them out to dry on a nice day. Dryers tend to bring the smell back up. I may evev just soak them in the washer and pour vinegar in. Then put them thru the wash cycle with a good detergent. I used to use Arm and Hammer but found Tide original got the smell out better.

It could be due to her medications, and/or most likely she is at least somewhat incontinent. Tell your parents to get her a needs assessment from the local agency on aging to find out what kind of assistance she might qualify for, a weekly bath aide might make a difference.