If the cause of death was unrelated to the accident and to the subsequent disability/injury, then yes, the amount that is recoverable is reduced. Here is how it works. There are generally two kinds of damages in these types of cases: economic damages and non-economic damages (these are also called special and general damages, respectfully). Economic damages are things like past medical expenses, future medical expenses that are expected to be incurred for future care, lost wages, future loss of earnings capacity, property damage, out of pocket costs, etc. Non-economic damages are what you probably know as "pain and suffering." This is compensation for physical pain, emotional distress, disfigurement, etc. If a plaintiff dies, then generally speaking, the non-economic (or "pain and suffering") damages expire also. You can't recover those. The estate or heirs or successors in interest can still recover economic damages. For an 84-year-old, who likely doesn't have wages or future earnings capacity, that is likely to be medical costs, which were probably paid by Medicare and/or Medicaid (Medi-Cal in California) anyway.
Now, if the death is related to the accident -- say, the cause of death is related to the "total disability" you mentioned -- then the heirs can bring a wrongful death claim on behalf of the themselves. However, causation may be an issue in such a case. (In other words, the defendant will argue that the death was not caused by the accident but by the elder's old age and pre-existing health conditions.)
You should keep in mind that there are certain exceptions to the above. The Elder Abuse Act, for example, allows the elderly to recover SOME pre-death "pain and suffering," but only in certain very limited, very specific conditions. If the potential defendant in your case is the apartment building owner, and this was not a special housing arrangement (e.g., senior housing or nursing home), then Elder Abuse may not be an issue.
This response is based on limited information. It is not meant as and does not constitute legal advice and does not create an attorney-client relationship.
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