In the Lodz Ghetto name search, Mendel is showing as deceased as of 07/02/1942. I cross referenced this with JewishGen Lodz hospital records, and there it shoes the same address, same year of birth, and same deceased date as the original site. Mendel name is spelled Mandel on Jewish Gen site and place of birth as Lodz. I therefore conclude that Mendel name may have been spelled Mandel Najman.
Mendel was listed at an unknown address when originally living in the ghetto. The only known address shown for him was Sulzfelder Strausse 7, Flat 31 (per Lodz ghetto list).
Per the Lodz ghetto list and the JewishGen hospital records, Mendel was admitted to the Lodz hospital on 06/29/1942. He ultimately died at age 21 of tuberculosis (per hospital records) in the Lodz ghetto hospital on 07/02/1942.
I believe his father was Chaim Zalman Najman (b 1883 or 1889 per 2 records) and his mother Ita Ruchla Najman (b 1885) per Lodz ghetto list. They were both listed as living at the same address at Mendel and both individuals passed away on 03/29/1942 and 03/24/1942, respectively. The same living address along with the ages of the 2 individuals makes it likely that these were Mendels parents. I also found a record of Jankiel Najman (b 1917), whom I believe to be Mendel's older brother. He died shortly after Mendel according to Lodz ghetto hospital death records on 07/31/1942 of tuberculosis, which is a highly contagious disease probably contracted from his younger brother. Chaim, Jankiel, and Mendel were all listed as being Schneiders (tailors). All of the above information, same addresses, occupation, age probablity, and death of 4 individuals less than 4 months apart lead me to believe that this is the family tree of Mendel Najman.