Walmart acted like I was lying about my mom DYING

I went to Walmart today. I went to try to return some items of clothing my mom had puchased before she was hospitalized and her health deteriorated. They still had tags and I had the receipt. It was the only reason I was there.

The clerk said it was past 90 days and she couldn't process it. Essentially the manager said the same thing, and so did the supervisor. The supervisor was the worst though. What a rude, unkind, uncivil woman. Event hough they still sale the exact same items (color and everything) she refused to do anything to issue a refund or store credit. She talked down to me, to the point I actually told her, "please don't talk to me as though I were stupid." She refused to help, treated me like I was lying about why I was there with the return, was R-U-D-E the entire time she spoke to me, but then said, "we like to try to help people" after she absolutely refused to hear me.

I walked back out to the car with my girls, put my head down on the steering wheel, and just cried. Why would I lie about my mom dying just to get some help from Walmart's indifferent CS?