According to this PDF document from the official site of the hall of Bacau the new name of the Filimon Sirbu street is GEORGE BACOVIA.
I do not speak Romanian, but google translate says that “Denumire veche” means “old name”. Also, it seems that this street had a few other old names beside Filimon Sirbu: “Gimnaziu”, “Regina Maria” and “Calea Moinesti”.
Here is the street in Google Maps, perhaps an aerial view helps your mom in recognizing it.
Credit:stackoverflow.com‘