I am so sorry for the loss of your mom, but very proud that you didn't drink, even with the temptation in your face.
I was a critical care/ER nurse for years (before my addiction) and I truly believe some people hold on until they know they're loved ones are okay (as okay as you can be when someone you love, dearly, is dying). Perhaps she stuck around a few days, just to make sure YOU were going to be okay. I've seen it happen, too often, NOT to believe it.
You gave her a wonderful gift. You were there for her, sober. The grieving period is hard, no doubt (my mom died at 50), but being able to deal with it sober is a gift we give to ourselves.
Hugs and prayers!
Amy