Why my mom, who weighs 600 lbs, keep her old clothes and picture after her weight loss...
Not quite sure what your asking here.
Keeping the clothes after WLS in my opinion would take up unnecessary room in the closet and draws. What is your mom going to do with clothes that fit at 600lbs after she loses her weight? If she wanted to keep one thing that's different some folks do that.
I kept my pictures because they were from different times in my life. No sense in erasing the past just because I was larger back then.
If she wants to keep them, it may be out of fear of regaining and not having clothes, having to re-purchase things. I kept one item )pants and shirt) as a memory of where I used to be. I have a photo of myself at my highest weight on my fridge, again to remind me of where I used to be to help me see that I never want to go back.