Originally Posted by NtL Rain
Follow her or take the towers. Buy wards, take 2nd tower. If she is still roaming, take 3rd tower.
This is another acceptable option. If you push hard enough, she'll be forced to return to the lane to stop your push. If she chooses to continue ganking instead of coming to defend her lane, then you'll push into their base and take an inhibitor, which makes your other lanes' minions stronger (giving them a slight pushing advantage) and gives you the ability to free roam without any worry of their minions pushing back out to your turret. Your turret is basically safe as long as the inhibitor is down if nobody returns to push it.