All your references to datum_B that I can see are at maximum material condition. A clearance hole just big enough to clear your hub at MMC would be an appropriate fixture.
You should look into training in GD&T. Your drawing looks like it was preparted to ANSI Y14.5M-1982. The datums are not called up that way on the 1994 and 2009 standards, which now are maintained by ASME.
You need some copies of the ANSI/ASME standards.
The (M)s in the datum boxes of your feature control frames indicate that the tolerances apply when the datum feature is at Maximum Material Condition (MMC). If the feature is not at MMC, you get a little extra slop.
If MMC had not been specified, you would have had to carefully design a centreing clamp.