This is actually one of the most common concerns families have before booking Char Dham and the answer is yes with the right planning. Tempo travellers are significantly more comfortable than buses for elderly travellers because the group stays together, stops happen on your schedule, and you are not rushing to match a tour operator's fixed timeline.
A few things that genuinely help: book a vehicle with good suspension, plan shorter daily drives of 5 to 6 hours maximum, and keep rest days in your itinerary especially after Kedarnath and Badrinath. Elderly travellers need acclimatisation time which private group travel allows easily.
Also carry basic medicines for altitude and cold weather. The inner yatra routes require local vehicles so your base tempo traveller parks at the dham entry points.
For families with senior members, Delhi to Char Dham by Tempo Traveller is honestly the most respectful and comfortable way to complete this sacred journey.