Please refer to the end of paragraph 7.5 of the datasheet: to reject both 60 an 50 Hz noise the oscillator frequency should be 48 kHz. You can calculate C that should be 12 pF (with R = 100k).
I've used a lot of 7107s, about 20 years ago, even before Maxim began to sell them, and the datasheeet was alway not-too-clear. I remember that the Teledyne version contained some errors the made me crazy..
Best regards