First of all, the nature of things, as you said, can be divided into two situations. In the first case, if you kick the old man, you will achieve fracture damage. Personally, it is more likely that this incident is classified as intentional injury, because as an adult, you should foresee the consequences of kicking people. For example, if all the kicked parts are broken, then underestimating the consequences of the injury obviously cannot be the reason for claiming that negligence causes death. In the second case, if there is nothing wrong with the kicking part, it is that you fell and knocked to death. In this case, you can claim that negligence caused death. But in any case, in terms of criminal law responsibility, it is necessary to bear criminal responsibility for the infringement in combination with the victim's special physique. No matter which of the first two charges is taken, your husband will bear criminal responsibility.
Secondly, you should do what you say. Whether you hire a lawyer or not, you must make two points clear. One is the injury of the elderly mentioned above, which is the key to the qualitative analysis of the case. The records on the death appraisal report issued by the forensic doctor will clearly explain the cause of death and the cause of injury. Your husband will be informed of the contents of this appraisal report, but generally his family will not be informed. On the other hand, no matter how qualitative, what you can do as a family member is to negotiate with the other family member, reach a certain compensation, get the other party's understanding, and thus obtain certain sentencing benefits.
Third, your husband's surrender can be mitigated or given a lighter punishment according to law. The victim's fault is also a mitigating factor. If the understanding of the victim's family can be obtained, the sentencing space is not small.
I suggest that you hire a lawyer to represent your husband, which is necessary to understand the case, provide legal help and represent you. After all, it means a lot.
The above text is for reference only.