Mobic (brand name) is an alternative to diclofenac. I know this because when I told my Spine Dr at my last visit that I could only take the diclofenac once a day or it upset my stomach, he said let's try this instead.
He scripted me 15mg of Mobic a day.
But I would get your grandmother into see a doctor. These are both VERY strong anti-inflammatories which have hordes of horrible side effects. I am not sure if Mobic would be a good choice for her as I do not know what other meds she is on. Anyway, it would be an option to mention to her doctor.
"We have not inherited the earth from our parents, we have borrowed it from our children".