YES, you should be OK traveling to Ladakh with a 7-year-old Child. In any case, please acclimatize yourself well.

Ladakh is not really 'dangerous for elders' place. It is high in altitude but as long as you are in good health with no ailments, you are free to travel to Ladakh as you would to any other place. Some general precautions that are applicable to everyone will apply to elders as well.

There could be some minor breathing problems when you'll reach very high altitude so I suggest you to take precautions and carry some emergency items accordingly.