Rutuals to help someone pass peacefully?

Trigger warning-death and dying.

My friend told me her brother is dying. Unfortunately, it's from complications due to his diabetes (infection that was ignored and turned into gangrene), so there is no recovery, unless he's one of the lucky 25% that does. I asked her if there is anything I can do, and she asked me to perform a ritual to give him peace and rest. I'm eclectic, so I'm pretty comfortable with anything y'all have to offer. Thank you.