I'm so sorry to hear that!

I suggest they get a Vitamix blender (powerful enough to break down tough fiber into a smooth consistency, even carrots and kale) and blend lots of fresh fruits and vegetables for him to drink. I personally regularly drink the following recipe and use it to make 2 different ones focusing on green or red for the final color.

16oz liquid (water or milk) 
24oz various raw fruit
12oz various raw veggies (roots/greens) 
2 scoops of vanilla protein powder
12oz ice

Optionally add dates to sweeten further.

Blend on speed 10 for 2 min straight, then when finished blend on low for a few min on and off to massage all the bubbles out so it's not foamy. This keeps in the fridge for a while so you can spend a few hours filling the fridge with smoothies to drink throughout the next few days.

I store mine in the fridge in pint mason jars with leak proof lids.