Go for jannu basti with medication. You also visit Ibhan Clinic

Yes , for some extent recovery is possible.  Chat for more detailed information

Before 80yrs of her age. she can expect reversal, healling n tone up

Chances are less as its completely tear... Still we can gie it a try...

Yes, Ayurveda offers non-surgical treatments for a medial meniscus tear, focusing on reducing pain, inflammation, and improving joint strength. Ayurvedic Treatment: Internal Medicines: Maha Yograj Guggulu – 1 tablet twice daily for joint repair. Ashwagandha Churna – 1 tsp with warm milk at bedtime for strength. Shallaki Capsules – 1 capsule twice daily to reduce inflammation. External Therapies: Mahanarayan Oil Massage – Apply warm oil gently on knees twice daily. Pinda Taila – Useful for soothing joint pain. Janu Basti – A Panchakarma therapy where warm medicated oil is retained over the knee to promote healing. Diet & Lifestyle: Avoid sour, cold, and processed foods. Drink warm turmeric milk daily. Gentle knee-strengthening yoga (under guidance). For better recovery, consult an Ayurvedic physician for personalized treatment.

Since your grandmother is having osteo arthritis,  complete tear of medial meniscus etc issues ,it is quite difficult to cure pain completely. Considering her age also i think the same. But we can somehow manage the pain by ayurveda treatment and proper rest. If she doesn't want to undergo surgery at this point you can go for that too.