Your grandmother can revoke the transfer the property with the help of SDO. But what is her age because after a certain age authorities trends not to consider their statements because of old age due to which sometime their memory comes and sometimes goes. The authority often takes decision which fits best for the old person irrespective of anybody's assertion!
So better consult a lawyer for better representation.
As a well-wisher of the wife's grandmother family, you may consult with all the other relatives to bring pressure, and join her in an old age home, contributing to the extent of their resources till a final remedy. When a son is refusing to take care of, one can not force him further for taking care of the mother, and taking action against son is secondary ad taking care of the grandmother is primary.
Currently she is been taken care by one of her daughter(My mother-in-law), but the Grand mother concern is like gave everything to her son who is not even just peeping in when she was ill and hospitalised