I'm not sure of DiL's situation obviously but, if there are practicalities such as packing up DM's clothes or picking up one of the many lesser 'admin' things there are to do (getting in touch with DM's local social groups for example) or looking after DiL's children, if she has any, when needed, if you are able to help, I'm sure that would be appreciated. I felt swamped by having to decide what to do with possessions, and the time it took, but SiL's help was such a relief. That was pre-covid though and sometimes it's really not possible to do anything much. So sorry for your loss.