How did you update?
The fact emonhub tried starting the serial connection at 9600 baud tells us the RFM2Pi you had was an rfm12b based device (assuming it worked previously and hadn’t changed that setting in emonhub.conf).
If you used the “Update emonBase” button from the emonCMS admin page you will have written the rfm69cw firmware to the RFM2Pi (see the Update EmonPi Button or Update EmonBase Button? thread for more detail) and as Robert says
There is already a compiled RFM2Pi FW for the rfm12b based devices, there just isn’t a update routine for it, try…
sudo service emonhub stop
sudo avrdude -v -p atmega328p -c arduino -P /dev/ttyAMA0 -b 38400 -U flash:w:/home/pi/RFM2Pi/firmware/RFM69CW_RF_Demo_ATmega328/RFM12_Demo_ATmega328.cpp.hex:i
sudo service emonhub start