Hi Sumita
Your question is a very challenging one: You are looking at some pretty significant yoga therapy practice, which is beyond the ken of this web site. You may want to check out this website:
Wheelchair Yoga. They offer therapeutic instruction for people in wheel chairs.
In the normal Yin Yoga world, we target the area between the navel and the knees: this won't work for your friend's husband obviously, but there may be many upper body postures that he can do. (Eagle Arms, Hands clasped behind the back, etc.) The basic premise in Yin Yoga is to come to an edge, become still and hold the position for time: this can be applied to the upper body, just hold for shorter periods, say 1 minute for a beginner.
I don't know of any yoga poses that target delirium and seizures however I can offer a few suggestions: first - yogic breathing. The slow
"ocean breath" can help reduce anxiety, turn off the stress system (the SNS) and activate the rest & digest system (the PNS). This may be very valuable for the student. Secondly, according to tradition Chinese medicine, the
Urinary Bladder meridian (UB) passes through the brain and disorders here may be addressed through stimulation of the UB meridian. Seated backbends and forward bends as well as gentle twists may help with the delirium. From an energy perspective, the upper body work will assist with heart issues and the backbending may assist with kidney issues.
These are just speculations on my part, but as long as the student's doctors are okay with the movements, there may be no harm in trying to do seated backbends and twists combined with some arm and shoulder movements. If the student is allowed to work on the floor, then Sphinx pose could be really good for him. Again, start slowly 1 ~ 3 minutes to start. You can assist him to do reclining twists and use bolsters to help him stay in the pose once you get him into it.
Good luck!
Bernie