Technically, this doesn't work
See the answer by Rubiksmoose on this relevant question; by a strict RAW reading, you can't move the mount between attacks. Even controlled mounts act on their own turn, and your attacks happen only on your turns- therefore, your process breaks down after your first Lance attack, because the mount cannot move the next 5 feet.
Additionally, you can't use a bonus action that triggers when you take the Attack action until your entire Attack action resolves, so you can't use the Shield Master shove attack before your second attack.
Furthermore, you may not be able to drop the Lance and draw your Longsword on the same turn, because dropping a weapon may consume your Free Object Interaction, though that issue doesn't have a definite resolution.
But if you rule otherwise, 110 feet
In the interests of giving an answer that might be more practically useful for your game: If we just ignore the above Shield Master ruling and possibly the Dropping a Weapon ruling, but run Mounted Combat by the rules, you can do the following.
The Worg takes its turn, during which it uses Dash and moves up to 100 feet toward the Human, remaining at Lance distance (10 feet)
The Orc makes a Lance attack.
The Orc drops its Lance and uses its Free Object Interaction to draw a Longsword.
The Orc dismounts (-15 feet movement).
The Orc moves 5 feet closer to the Human, so that it is now within 5 feet.
The Orc uses its Shield Master maneuver to shove prone.
The Orc uses its second attack from Extra Attack to strike the prone Human with the Longsword.
The Orc has 10 feet of movement remaining.
This is possible because the Worg's movement is entirely separate from the Orc's.
If you rule otherwise for Mounted Combat as well, you can start 105 feet away, use the Worg to move 95 feet, attack with Lance, and then move another 5 feet on the mount before completing the rest of the process. The difference in this case is pretty small.