It turns out our neighbor and her son who died had a lot in common with us in many ways, so the gardening is really just a good excuse to commiserate and empathize, with lots of side benefits.  For example, we helped her break down and clean up some major trash, and she gave me a large woody night-blooming jasmine tree!  I could never afford one, and I love it.  Also, a piece of raw amethyst, my birthstone!  I also scored a long garden hose to extend ours, ferns to transplant, and all kinds of other gardening stuff.  E is going to help her out eventually with painting the garage and house interior.  The neighbor will pay for supplies and labor.  Mostly we just listen and help her process grief.  It gives new meaning to being neighborly and garden therapy.