which food items give during diarrhea of 9 month baby

Rice, banana, apple are stool binders, so you can offer rice porridge, steamed apple puree, banana, curd is a good probiotic will help the gut, so offer curd.

What to Feed When Your Child is Down With Cold, Cough, Fever or Diarrhea?
Please read this article

More liquid items should be given to baby. Barley water helps during this time