Blood in stools + watery consistency of stools is found in a condition known as: 

Dysentery is an intestinal infection that causes severe diarrhoea with blood and mucus that may be found in the stool. In diarrhoea, loose, watery stools along with abdominal cramps occur. Other symptoms of dysentery include abdominal cramps or pain, nausea, vomiting, dehydration, and fever.

So the correct answer is 'Dysentery'.