Dear Anindita, acute mountain sickness does not matter with respect to age, gender or physical fitness. It can happen to anyone and of any age. So, yes, as much as you can go yourself to Ladakh, you can surely take your parents provided they are in healthy condition and can endure the fatigue of this long journey. You should plan a relaxing and comfortable itinerary for your Ladakh trip when taking your elder parents.
If they are on medication or have any existing illness, make sure you consult your doctor only after the doctor’s approval travel to the high altitude places carrying proper medication.