Part of the reason that date was selected was to accommodate the arrival of Meir Brand from Israel, one of the then children that Rubinsztejn saved.
Although both were living under Gentile indentities in Budapest when they met in 1944, they would become family, bonded by their circumstances and liberation. They call themselves mother and son.
Read the highlights of their story in an article on Jewish Ideas Daily:
Berta made her way to Budapest in 1942, where she began working for the Zionist underground through the youth movement Dror Habonim. She assumed a Gentile identity and the name Bigota Ilona and wore a crucifix around her neck. […]
In May, 1944, Rudolf Kasztner made a daring deal to provide trucks to Adolf Eichmann in exchange for the safe passage of Jews out of Hungary by train, to the neutral country of Spain and ultimately to Palestine. The goal of Dror Habonim became getting Jewish children onto Kasztner’s train.
Meir Brand was one of those children. He was born in 1936 in Bochnia, Poland, and his family was forced into the Jewish ghetto there in 1942. After the 1943 Warsaw Ghetto uprising, Meir remembered, “everyone knew the whole ghetto”—in Bochnia—“was going to Auschwitz.” Soon afterward, “the whole family,” three sets of parents, “convened to decide what to do.” They determined that one child of each set of parents would escape.[…]
Meir, homeless like hundreds of other Budapest refugees, took shelter under the city’s bridges.
Berta found him there after seven months—alone, frozen, and covered in blisters. “Jude?” she asked. “I am Dudac Josef!” he answered.
“I didn’t trust anybody,” Meir remembered, “because I was under such strict instructions not to connect with anyone.” Still, “I trusted Berta. Why, I don’t know.” When Meir said he was Dudac Josef, Berta thought, “That means, ‘I am a Jew.’ Somehow I knew he was a Jew. And I said, ‘I am Bigota Ilona.’” About that moment, Berta later told Meir, “I looked you in the eye and said to myself, that’s it, you’re mine.”
The train carrying Berta and Meir, with 1,684 passengers in all, was diverted to Bergen-Belsen. There, Berta recalled, “I was with the halutzim,” while Meir was in a barracks with the other children. Still very weak, he couldn’t clean himself or eat properly. Berta devoted herself to his care, and nursed him back to health.