Question

My grandmother is hard...hearing

Answer 1

My grandmother is hard of hearing

Answer 2

The answer is: My grandmother is hard of hearing.  The preposition “of” will be used here.

The meaning of the sentence is my grandmother is hearing challenged.

The use of the phrase “hard of”  is a phrasal verb and it is helping in emphasizing the meaning of the sentence  beautifully.  

The use of phrasal verb, “hard of” is a good substitute of the harsh word short.