They make a product called goof-off that is great for these kinds of things.You can try wood polish and see.But I think you may want to just try and blend it in with semi-gloss varnish,just sand that area a tiny bit and use a foam brush and brush on a tiny bit of the varnish.
It will still be most likely noticeable but not as bad as a dull spot.
i own my own painting business so we do alot of wood work and such,a wooden table is really no different than a oak door.
other options are to get it re-done.There should only need to re do the top.Don't fall for the BS that they need to do the legs and such.
Or redo it yourself,by sanding the top with a 120 grit sandpaper lightly across the whole top (just lightly rub a few times from 1 end to the other)should take about 2 minutes to sand it no more and then use a nice semi-gloss varnish and a good quality brush.
Hope this helps

In the future a nice website is www.crayola.com and then click on the crayon that says Helpful Information. The you will se a spot that talks about stains. They ask you what caused the stain such as crayon, marker, paint etc. Then they ask you what the stain is on such as clothes, drywall etc. Rubbing alchohol takes perm marker off a lot of things, but I think you still would have been refinishing your oak table. My daughter drew on latex paint with perm marker and the rubbing alchohol worked great. They said just dip a Q-Tip in and rub very gently. It worked great.

WD40 takes crayon off latex paint.

Good luck,
Devildog