the crashinfo file can be deleted without impact, it is useful for troubleshooting and debugging crashes, but not needed for the operation of the IP phone.
DHCP option 150 specifies the TFTP server on which you have stored the firmware. So the IP address (or addresses) need to be the ones that correspond to the respective TFTP servers. In your example, your TFTP servers would be 192.168.125.1 and 192.168.120.50. If your TFTP servers have different IP addresses, or if you want to use different TFTP servers, change the IP addresses accordingly.