take her a casserole or some hearty food that she can easily reheat
it will be very difficult for her to be thinking straight ..
put it in a container you don't expect back .. put reheat instructions on it .. make sure it's something that can be frozen if necessary (sausage casserole is a good bet unless veggies)
if you know someone who knows her better than you then maybe you could ask them to take it round
you just need to be there without forcing yourself upon her .. it is tough .. don't avoid her though .. express your sorrow and offer actual help not useless 'anything I can do to help'