The doe is having a tough time with 2 existing litters and another possible litter, and the loss of her partner. She may be pregnant again if dad was left in with her. I would suggest she is neutered for her own health and wellbeing, when the latest litter is old enough.
I would be wary of too much intervention while there are babies in the nest, as that may cause her more stress and it could affect the babies. Just keep an eye on her - make sure she is eating / drinking as normal. If she is used to getting attention, then continue as usual, or whatever she will accept.
What is the plan for the babies? One or two could be kept, neutered (boys at 3 months, girls at 6 months) and paired back up with mum. Rabbits do better with their own company.
As for dad - I'm sorry for his loss. Were there any clues as to the cause of death? Was he vaccinated? It is important that all rabbits are vaccinated annually against 3 main viruses (Myxo, RHD1 and RHD2) as they can cause sudden death. If mum and the older babies are not vaccinated, I would suggest a vet visit as a matter of urgency to get it done.