Last hope is always God or the Supreme Nature - whatever you call it.
If you are in India, commonly available Ayurvedic Medicines which are simple and economic will set it right. I m 100% confident.
If you are outside try to get it online.
Tab
Cystone, Tab Neeri, Gokshar guggul pill : 1 tds each with lots of water.
Avipattikar chooran ( a herbal powder) 1 tsp TDS with honey or
cold milk or water.( this may be little bitter).
If possible get Liquid Chandanasav too and give her 10 ml + equal water TDS
So two kinds of tablets, one tsp of herbal powder, 10 ml of liquid thrice a day for 4 weeks will revive the motivation in your grandma to live happily. These are pure herbal preparations, safe, side-effect less and economic. May not be tastier because these are non synthetic naturals.
Hope it will help your grandma 100%. For availability problems, you may further contact us.