I don't know an awful lot about physics but I'm educated enough and have read/watched/played enough SciFi to understand the basics. It is my understanding that oxygen is running out causing people to eventually die of lack of oxygen plus crops are dying. So in the end, how did whatever was tapped in Morse Code to Murphy enable her to do what she did? And I should probably also ask what it was that was tapped to her as well.
You can see my answer here for a lot of details on the physics problem they were trying to solve, but the short answer is that they had found gravitational "anomalies" suggesting that the gravitational constant G actually wasn't completely constant after all, and if they could learn to control it, they could find a way to leave the dying planet in massive numbers by temporarily making gravity much weaker (so the energy needed to achieve escape velocity would be much smaller). But to understand how to control it, they needed a theory of quantum gravity, and to find the right theory they needed measurements that could only be made near the singularity of a black hole (again, my answer above goes into more detail). So Cooper was giving Murph information from TARS' analysis of measurements they made inside the black hole, before they were rescued by the tesseract (which had been created by advanced beings, possibly descendants of humanity, in a higher spatial dimension).
In The Science of Interstellar by physicist Kip Thorne, chapter 31 talks about them using quantum gravity to decrease the Earth's gravity and get the huge colonies off the Earth:
Early in Interstellar, when Cooper first visits the NASA facility, he is shown a giant, cylindrical enclosure being constructed to carry thousands of humans into space and house them for many generations: a space colony. And he's told there are others being constructed elsewhere.
"How does it get off Earth?" Cooper asks the Professor. "Those first gravitational anomalies changed everything," the Professor replies. "Suddenly we knew that harnessing gravity was real. So I started working on the theory—and we started building this station."
How did it get lifted into space? The key, of course, was the quantum data (in my scientist's interpretation, the quantum gravity laws) that TARS extracted from Gargantua's singularity (Chapters 26 and 28) and Cooper transmitted to Murph (Chapter 30).
Murph must have figured out how to reduce Newton's gravitational constant G inside the Earth ... In my interpretation, with Newton's G reduced inside the Earth to, say, a thousandth of its normal value for, say, an hour, rocket engines could lift the enormous colonies into space.
As a byproduct, in my interpretation the Earth's core—no longer compressed by the enormous weight of the planet above—must have sprung outward, pushing the Earth's surface upward. Gigantic earthquakes and tsunamis must have followed, wreaking havoc on Earth as the colonies soared into space, a terrible price for the Earth to pay on top of its blight-driven catastrophe. When Newton's G was restored to its normal strength, the Earth must have shrunk back to its normal size, wreaking more earthquake and tsunami havoc.
But humanity was saved. And Cooper and ninety-four-year-old Murph were reunited. Then Cooper set out in search of Amelia Brand in the far reaches of the universe.
So how in the end did whatever Cooper tap in Morse Code to Murphy enable her to do whatever she did to get a space station out near Saturn and have it named after her?
He provided her with the data from the black hole. It was the missing piece she needed to finish the equations that would enable manipulation/control of gravity. That control over gravity provided humanity with the tools needed to build huge space stations, one of which was named after her.
And I should probably also ask what it was that was tapped to her as well.
The data from inside the black hole, as gathered by TARS.