Friends need help on pending I485 for more than 2 years now, any input will be helpful.

My friend (from Nepal) applied her I485 on the employment basis on EB2 with approved I140. It’s been 2 years plus and still her I1485 is pending, she contacted USCIS multiple times; opened Service requests, spoke with L1 and L2 officers, did follow up via congress man, senator and homeland security office also and all they said is she has to wait as USCIS is waiting on her background clearance. But they never clarify why it taking so long to complete background and they said there is no time limit for waiting as well

I found lot of cases on ttrackit.com about the pending I485; they are talking about WOM (Writ of Mandamus - civil lawsuit that requests a federal court to force USCIS to adjudicate a delayed pending application in a given period of time). It seems WOM cost lot of money and it’s not guarantee that your case will be approved.

So my question is WOM is the last thing she can do now? Have any one gone through the same situation?