Many thanks for your query.
I hope that all is well with your mom.
Typically following surgery, patients are put onto a liquid diet, followed by a light, low residue diet and then discharged home. Once at home patients are able to resume their usual diets. As her IBS was well-controlled prior to surgery, I would suggest that your mom continues to eat as previously tolerated as well taking the probiotics. Sufferers of IBS benefit from a high fibre diet. I would encourage wholegrain cereals, oats, brown rice and pasta, wholemeal bread and plenty of fruit and vegetables. Dairy and wheat should be taken as tolerated. Remember plenty of fluids are important - aim for 2-3 litres per day.