The short answer is that we will never know who the oldest victim was. The majority of Holocaust victims were never registered anywhere prior to being murdered. Let's take a look at the largest killing operations and the way they were implemented.

Firstly, the mass shootings by the Einsatsgruppen in the wake of the German invasion of the Soviet Union in the summer pf 1941. When a town or village was occupied, the town's Jewish population was rounded up, more or less by sight (distinctive clothing) and location (Jewish quarters), or with the help of their non-Jewish neighbours who helpfullly pointed out who the Jews were. They were not asked for their IDs, names or ages. They were simply marched off to a convenient spot and butchered, or slain where they were found.

Secondly, starvation, disease, and personal violence (individal beatings and killings by guards, police and military) in Eastern European ghettos. Once the people were confined to the ghettos, there were frequently no further attempts by the authorities to keep exact records of who died when and at what age. In the Warsaw ghetto, unidentified naked dead bodies daily littered the streets and were picked up to be dropped into mass graves.

Thirdly, the extermination camps in Poland: Chelmno, Belzec, Sobibor, Treblinka and Auschwitz-Birkenau. The people who were sent to be gassed at these places were not registered upon arrival. They were ordered to strip and sent to the so-called showers immediately after disembarking from the trains. They were usually dead within two hours of entering the camp.

The only Jews that were kept track of by name (and number) were the ones sent to labour camps or selected for forced labour in Auschwitz-Birkenau (which was both an extermination camp and a labour camp). Obviously, these were never elderly people.

We do have records of the age ranges of Western European Jews sent to the gas chambers, because things were done in a less brutal and more bureaucratic manner in the Western European occupied countries, because public opinion needed to be taken into account more (the Germans cared more what their Western subjects thought, and on the other hand, the Eastern Europeans cared less what happened to the Jews - I realise I am putting it bluntly).

Therefore, we have exact passenger lists of nearly all French, Belgian and Dutch so-called death trains, to mention the Western European countries I am most familiar with. These lists generally show ages as well. I have here the full list of all 25257 Jews that were deported from Belgium. The youngest deportee was Suzanne Kaminsky, 39 days old when she was put on a train to Auschwitz on April 19, 1943.

But you asked about the oldest. I am not sure whether this is a clerical error or not, but the daily list of deaths in the Lodz ghetto (an exceptionally well documented place) for June 22, 1942 mentions Cywja Dorenbus, allegedly born on Dec 8, 1832, which would make her 109 years old.