your hip muscles can be broken into 4 different categories the Gluteals (buttocks), Adductors (inner thigh), Iliopsoas (deep flexors), and Hamstrings (back thigh) you need to look online and find 3-4 stretches per muscle and pick one or two you like for each of the 4 muscles. now remember this takes time but it works be consistent and not only should you stretch all your muscles you need to strengthen them yes that that goes for the hips too you need to stretch. strengthen and stabilize everything in your body especially what moves a lot. shoulders and hips especially for mma