Vss for IR2110
You surely should have some Vdd bypassing. With separated Vdd and Vcc supply, 0.1 uF should be enough for Vdd, but I would prefer 1 uF ceramic near to the chip. In case of common supply, a larger bypass cap (e.g. 10 uF) is suggested by the datasheet anyway.
As another comment, although 3V Vdd supply is allowed by the datasheet, you won't to use voltages below 5 V if you consider the timing diagrams. The actual chip behaviour can be even worse, according to my observations.
In case of separated Vdd and Vcc supplies, separated control (VSS) and power (COM) grounds may be used as well. But only a limited voltage difference is allowed between both ground pins. IRF document DT97-3 gives some considerations regarding safe operation of the IR2110. Connecting both ground pins near to the IR2110 should always work, of course.