If that clinic really told her they had 100% success rate with DE, she should change clinics because they are lying to her. Nobody has 100% success rates. The best clinics in the country have about a 75%-80% success rate with donor eggs and the more average ones have in the neighborhood of 50%; you can look that up on www.SART.org (go here, then click on a state and scroll to the clinics you want to check:http://www.sart.org/find_frm.html
Even apart from the fact that it sounds like they lied to her, the clinic your friend went to does not even have its success rates posted on SART.org--that makes me very suspicious. I would never waste my time and money on a clinic that doesn't reveal its success rates. Based on the fact that this is apparently a small no-name clinic (sorry, I'm blunt), and they don't reveal their success rates but they claim it was 100% last year, there are two possibilities here: (1) they're just lying, or (2) they do hardly any donor egg cycles at all, but last year they did one or a handful of them and by coincidence all the women (like... all three of them or whatever!) happened to get pregnant. And it doesn't matter whether it's (1) or (2) that's true; either way she should go to another clinic. You can't go to a clinic that lies to you, and it's a waste of money to go to a clinic that doesn't have much experience with the thing you need.
As for her cycles, I'm not a doctor but I've researched infertility up the wazoo and I have never heard of an immune issue (in the sense of the immune issues that sometimes cause miscarriage or failure to implant) having any effect on a woman's menstrual cycle. When the cycle is wacky, the hormones are wacky--not the immune system. Something's obviously wacky in her system, since her cycles are irregular, but I highly doubt that's why her DE cycle didn't work. DE usually works but not always; depending on the clinic, there's between a 20-25% and 50% chance of failure. Your friend just fell within that 20-50% of failures. It's not her fault. But she should change clinics for the reasons mentioned above, although it might be worth trying a FET cycle with whatever is left. I just wouldn't do another donor cycle with them.