it may not seen that strenuous to you but it obviously is to her. Did you get her physician’s okay for exercise? Has it been like this from the start. Or has it changed?
On the assumption that she is cleared to exercise: It is necessary that you dial the intensity down. There are several options.
Can you train her for 30 minutes on two different days? Can she do the cardio by herself on alternate days?
When you strength train her, you could intersperse the strength training with balance training intervals where she does not lift weights. You could even stretch in between even though I am not a great fan of that, but, sometimes you have to roll with the punches.
Dealing with conditions like that is always tricky. You have to find the point where she does not feel incapacitated afterwards. The risk is that she drops out altogether, and that will be to her detriment in the long run.
Wishing you and your client good luck.