Can I sue someone from another California county other than from the CA county where I reside?

Where you sue defendants for damages for wrongful death is where any of the defendants live, or in the county where the injury causing death occurred. There's no exception for a plaintiff's/survivor's disabilities.

Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.

Venue is proper where the defendant resides, or where the injury took place, as the previous answer stated. However, the courthouse where the lawsuit is filed and where the trial will take place should not deter you from filing a lawsuit. Most of the work in any civil case involves discovery requests through the respective attorneys and deposition which can be taken also in the attorney's offices.

The chances that you will ever need to travel to the courthouse other than for the trial of the mandatory settlement conference right before the start of the trial is slim to none.

So do not let the physical location for the filing of the complaint stop you from filing the lawsuit.