The grubs you are seeing are most likely the larval stage of masked chafer beetles. The ¾ inch adult beetles are golden brown in color, with dark brown heads and hairy undersides. The grubs are whitish in color, with brown heads and legs, dark stripes on their backs, and bristles on the undersides of their posterior abdomens. The fully grown grubs are about an inch in length, and are c-shaped.

Physical removal of the grubs from the beds is the first line of defense. Hand-picking is a great approach. You can also get help from birds and other predators by turning over the soil to expose the grubs.
While the grubs can damage vegetables, if you can keep the grub population under control through hand-picking, your vegetables may do fine.

One additional note of caution: Be careful when it comes to amending the soil in your beds with fresh compost (e.g., made on-site). That compost could contain masked chafer eggs. The larvae (grubs) will locate and feed on roots after they hatch. Before applying compost, be sure it has been properly prepared with sufficient heat to decompose the organic material and to kill insect eggs and other organisms.

Excerpted from, and for further information:
 https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26574