Recurrent obstruction, mass per rectum and diarrhoea in child -
Answer is 'a' i.e. Intussusception Although I could not find any documented evidence of diarrhoea in Intussusception, the given picture goes with intussusception only. Intussusception has been seen to complicate cases of gastroenteritis (Nelson 17/e p1242). Probably this can explain the diarrhoea.
Intussusception
Rectal prolapse
Internal hernia
Haemorrhoids