"my 60 year old male friend wakes with extreme cramps in his right thigh and leg its so bad that he cries and screams I buy him bananas avocados cherry juice and he drinks lots of alkaline water what can this be?

Many things! From restless leg (requires meds), through calcium, magnesium, potassium, and iron deficieny, all; can cause these symptoms. Hydration via water is important, as are meds that may deplete the mentioned minerals. Adding magnesium (oxide) 400mg/day may help. Remeber, iron deifiency can be present without anemia.
Nocturnal leg cramps. I can tell how you can prevent it. All patients tell me that they get thse leg cramps about 3-6 am when they are in bed streching while awaking. Ask your friend to stop streching with "toes go south", but strech in "toes go north" position. I promise you you will be able to prevent these painfull condition. Do not eat so sugary stuff!