In a search for L* Hamer, Luba was the only one that up that was both the right gender and born in the right timeframe to have attended School #19A.
I expanded the search to fuzzy parameters and also came up with Liba Hammer, who I presume is the same as Luba because they share the same birthyear and address.
Luba lived with her father (Jankiel, b. 1887), mother (Estera, b. 1890), and siblings--Frajda (b. 1921), Moszek (b. 1925), and Menasze (b. 1930).
All, in addition to having the same address, had the same deportation date and transport number--July 19, 1942. There is no corresponding deportation listed for that date in secondary sources. However, according the notes, the family also lived in Biala Rawska, so perhaps they were transported on a separate date/deportation from there.