It depends. You can try a visitor's Visa. As far medical conditions if only immediate family they may consider so I doubt if they will give any priority. I know a family, her son was dead here in Canada. She thought they would definitely give her visit Visa but was rejected. But tried after few months on a separate occasion of happiness, was given a TRV. It is a hard fact trust me..I know them!
So trying won't hurt your present app however say they gave you a Visa, will you stay an outland applicant? Think? or they will transfer files backwards? Or sure you will have to return back to India, which mean 1st ticket will be a RETURN ticket,. Then another ONE way ticket. Remember you have to show RETURN arrangements, ties back home, income tax returns, property value or few other factors ; forcing you to come back from a visit. They are not likely to consider transferring files, else most ppl will have done this way! My wishes+prayers that your in-laws come to normal health soon.
