Does blood money or expiation become obligatory for someone who caused a car accident 30 years ago that led to the death of two people, knowing that he has fasted and given charity, does not know the identity of the deceased, and does not possess sufficient funds for blood money?

Your error necessitates two blood monies and two expiations. The two blood monies are to be paid by the 'aqilah (male agnates of the killer) and delivered to the families of the two deceased, unless they forgive. The expiation is mentioned in the verse: "And it is not for a believer to kill a believer except by mistake. And whoever kills a believer by mistake – then freeing a believing slave and a compensation delivered to his family [is required] unless they give [it up as] charity. But if he was from a people hostile to you and he was a believer, then freeing a believing slave [is required]. And if he was from a people with whom you have a treaty, then a compensation delivered to his family and freeing a believing slave. And whoever does not find [one] – then fasting for two consecutive months as repentance to Allah. And Allah is ever Knowing and Wise." (An-Nisa 4:92). Due to the impossibility of freeing a slave, you must fast for two consecutive months for the second deceased. Giving charity does not suffice for blood money, nor does it lapse with time or lack of knowledge of the family. You must search for their families to pay the blood money, and if you do not find them, then give it as charity on their behalf.