Ndiaye is on 45 grand a week.Money just isn't the type of compensation that it used to be within the PL. You can very easily spend 50 - 100 million and do nothing but downgrade, and before you know it, you're in a West Ham, Spurs, and Everton until very recently situation.
Ndiaye has three years left on his contract and is clearly happy at Everton. He won't rock the boat. So it's all down to how TFG want to play it? Garner's got four years left on his contract, and United won't pay what we would correctly ask for with regards to him. United will have other targets and aren't going to obsess over Ndiaye and Garner imo.
If he's not rocking the boat now he will be.
If the club aren't in talks with his agent about a vastly improved deal then they should be.