How can C prove the Xerox copy of promissory note?

A gave money to B by getting B's signature on a Promissory Note. After A’s death, his wife and daughter (C) survived. During this period, C was quarantined, and A's wife was depressed. D came to A’s house, took the promissory notes and other properties, collected money from B, and gave the original promissory note to B. However, the money was neither given to A's widow nor to D. Later, A's widow also passed away, leaving D as the only legal heir. C filed an FIR (IPC-420, 406, etc.) and a civil suit against B for recovery of the money, with D named as a defendant. The court has marked the FIR as evidence but not the Xerox copy of the lost promissory note. The Xerox copy was taken by C after A’s death and before D took it. Can you suggest any provisions or case laws under which the Xerox copy can be marked, and C can get justice? Note: B did not attend the court proceedings, so the case is being considered ex-parte.