I don't think that Ancestry.com has San Francisco newspapers? (only the Daily Alta California for the late 1800s and only a few issues)
You can request Nicholas Mertens' obituary from the San Francisco Public Library: http://sfpl.org/index.php?pg=2000049301
Did Lillian Mertens also die in San Francisco?
I'll see if I can find anything on the Sullivans...