I am so sorry for your loss. As someone who was close to her grandparents and spent a significant amount of time living in their house while I was growing up, I know how difficult it can be.

You really need to do something nice for yourself, but eating isn't it. Whenever I am in a similar situation to the one you are in, I remind myself that eating too much will only make things worse. Then I try to think of what I can for myself that is physical but doesn't involve eating. For me it often involves getting outside in the fresh air, but we are all different, so different things work for different people. For some people a massage helps, or a long nap, or something like that.

Can you put off the test for a couple of weeks? You've just been through a big shock and having extra pressure now is probably not very helpful.