Someone asked me a GREAT question - what are shomrim. So here it goes - according to halacha, it's a deceased person should never be alone, from the time they pass away until the moment they are buried. So Jewish communities or Jewish funeral homes will organize shomrim - Jews who occupy the deceased. The person will spend time studying or saying tehilim. It's one of the most important mitzvot a Jew can fulfill because there is no reward for it in this world - meaning the deceased can never pay you back. It's part of the larger body of mitzvot that fall under kavod ha-met - honoring the deceased.
Please let me know if you have further questions.