I don't think your parents gave you the money because you helped them, but because they loved you. I hope your kind acts toward them was out of love as well.
How you spend it is entirely up to you, I personally would take a trip, possibly a cruise. Or is their a cosmetic procedure you would enjoy splurging on? I also love the gold bracelet idea with the engraving.
I sm very sorry for your loss. You can take comfort in knowing you lovingly cared for your parents.