Do You Recommend Ultrasonic Cavitation for Ankles?

I am  not sure where you read about ultrasonic cavitation but the only device approved in the U.S. for permanent fat reduction with ultrasound is Liposonix. Ultrasound can be used to affect fat cells with either heat or a property called cavitation, but this is more difficult to focus and control with precision. Liposonix uses a mostly thermal technique to destroy the fat cells. It is done in a single treatment and the body then reabsorbs the tissue.

Based on your photographs, you have significant abdominal wall laxity. It is very difficult to assess if you have enough skin for a full abdominoplasty (tummy tuck) without examining you. You need to see a board certified plastic surgeon to be assessed.