Sorry to hear about your loss. There is much more information necessary to evaluate a possible case. For example, how did he get back in the house. If facts support the case, in California the children could sue. Strict time limits apply, and you should seek the services of a qualified lawyer in the jurisdiction where the incident took place. Do not delay. It is important to get right on these investigations. Best wishes to you and your sister.
I do not practice in GA so I can only provide general information. You should contact a local personal injury attorney.
Wrongful death cases are governed by specific statutes in most states, like who can actually file suit, and who is entitled to receive compensation.
Good luck, I'm sorry for your loss.
I see you are in Summerville. I went to elementary school at Menlo many years ago, and though I've been in Atlanta many years, I occasionally get back to Chattooga County. Just about a month ago I took my dad back to Menlo for a reunion with some of his former students.
Normally under Georgia law, the wrongful death claim is controlled by the surviving spouse, and normally a claim against the surviving spouse by the children of the deceased spouse is barred by spousal immunity. Sometimes creativity can get past apparent barriers, but it takes a lot of detailed examination of facts to even begin to exercise such creativity.
There are not enough facts in your question to answer the question of whether there was a negligent act that caused the death, but you as the children may be able to take control of the Georgia wrongful death claim under the Court's analysis in Belluso v. Tant, 258 Ga. App. 453, 574 S.E.2d 595 (2002), The Superior Court has the equity power to take the claim from the wrongdoer and to preserve the right of recovery at the same time. It is within the equity power of the Court to allow the parent of the deceased to sue the negligent spouse for the death of the child, in effect allowing the Georgia wrongful death claim to leap over the wrongdoer.
If there are facts supporting a claim of negligence, you may be able to bring the claim.