Can a GM title be given to someone after he dies? Can a GM title be given to someone after he dies? For example can Rashid Nezhmetdinov receive a GM title for his contribution to Chess?
Yes, it is possible. FIDE can award the title of honorary grandmaster, based on a player's past performances and/or other contributions to chess.

Most of the honorary grandmasters were still alive when they were awarded the title. However, there are two examples where the title was awarded posthumously: 
GM Rudolf Maric and GM Karoly Honfi.