If there is enough length to the cast iron pipe sticking out of the hub, you can rent a snap cutter, cut it off, then use a no-hub connector to attach your abs stuff.
Another alternative is to dig out the old CI from the hub, and use a Fernco dognut, if you can find the right size. basically, it's a compression fit and getting the right size dognut is the chore.
Or, cut the entire hub fixture out and replace with abs, then attach what's left with the no-hub connectors. If this is underground, then you can use the fernco fittings. Both attach in the same way, but the no-hub is required above ground as the metal sleeve keeps the pieces aligned. The fernco needs the soil and proper backfilling to do that task.