This is really sad to read whats happens, my condolences.
Well, even when the computer destroyed, maybe there is a way the hard drive is still operational, and you can just connect it to another computer and have access to your fathers wallet.
Now, be patient, do not rush, and if you need help, it is better to look for someone in who you can trust, and much better if you know the person physically, ok? (a friend of a friend, a family member…)
There is a dramatic situation and they are always bad guys trying to get advantage…
Also, if you have his phone, maybe he had a wallet installed on it.
Try to search on the disk for wallet.dat file, or privatekeys backup, even some people have files with their wallet passwords as backup.
Hope this information help, any question you have post it on this forum and we will help you, but remember to not post sensitive information like privatekeys or things like that.