Yes, no (but that's not a totally objective topic), yes, if the operation that caused death was under certain situations. FWIW, VERY rare these days compared to when the BGen was in the fleet.

They would still receive their SGLI (Servicemembers Group Life Insurance) which was $35,000 when I served, considerably more now. There are additional indemnities for being killed in a war

If he did all the Marine would say is you're right, I'm Recon. Better than special forces

Force Recon may not be a part of SOCOM, but go and tell a Force Recon guy he isn't special forces haha.
"The spirit is willing, but the flesh is spongy and bruised."

LOL
But MARSOC didnt exist when this movie was made

Theya aren't special forces. MARSOC has it's own Marine Special Forces Teamhttps://en.wikipedia.org/wiki/United_States_Marine_Corps_Forces_Special_Operations_Command
Marine Force Recon Units just do military intel missions.

Does Force Recon exist? Sure -
http://en.wikipedia.org/wiki/United_States_Marine_Corps_Force_Reconnai ssance
Do they carry out black ops work - yes.
Are the families denied benefits - well, if they were, we wouldn't know. The movie story is about Marines who die in operations that are too illegal for the government to admit to anyone. Any family member would simply be told that the Marine died in an accident.
Fichtre! Voila qu'on me tue mes morts.

Anything is possible.