He is such a cutie
I suspect mommy has met with a sticky end, which is why he is wandering around.
Our Humain Society here has a wild life department that takes care of these little ones and tries to re-integrate them into the wild.
Hopefully your HS or SPCA has a similar department.
If not, then maybe an outdoor hutch (exercise pen with tarp over it in a pinch) and bunny food from the pet store. At least he will be safe from preditors that way, until he gets bigger.
Please keep us updated on the little one