Aw, Im so sorry for your loss! Those things are always tough! I don't think any of your thoughts around this are selfish or insensitive. Going through a difficult time doesn't mean that you have to stop caring for yourself. In this instance, I would say that perhaps you keep going with the program 'as best you can' and then start again when you're feeling better. That means that at the wake, if there are veggies and maybe some protein that you could eat, choose that instead of the cake/pie/pasta, but give yourself the room to just do the best you can. It's not unusual in grief to not have an appetite so it might just be that you can manage with some purse snacks and depending on where you're staying, a hardboiled egg or two... I think that just making good educated decisions in the SPIRIT of Whole30 without beating yourself up about the rules is probably going to serve you better at this time... and we're always here for you when you're ready to come back and to cheer you through this tough time too!
I'm so sorry for your loss. Sometimes the routine of Whole30 helps eliminate the guilt of binge/comfort eating because you know you are fueling yourself in a healthy manner, and gives us something to focus on while we're grieving. Can you eat before the wake or bring your own dish to eat? Maybe offer to help her with the food so you can get some Whole30 meals in there?