My friend 58 yrs. She has knee joint pain. Doc wants to operate. She wants to wait. As she feels it's too early seeing her age. She is able to manage.

Maybe. Depending on the degree of knee involvement, perhaps physical therapy may allow relief. Also, arch supports may help knee problems if there is a problem with flat feet! good luck.
Wait. If you can live with the pain i.e. It does not affect the quality of your life, leave it alone and wait.