Well, her first choice was made when she chose to flee the palace instead of standing up to Rahvin. And this was realistically her only choice - she tried standing up to him and ended up being very publicly humiliated, and her actions under compulsion had both alienated her allies and weakened her legal position. While she put it down to being lovestruck, she deserves a little credit for at least being able to see that she could not fight Gaebril, even if she didn't understand why.

After fleeing she also only had two choices: she could attempt to oust Gaebril and retake her throne, or she could abdicate and live the rest of her life as an anonymous commoner. Again here I think she made the right choice, though I disagree with the way she went about it. In abdicating she would have turned her back on her duty and let the whole mess fall onto Elayne's shoulders, and though she had really, really screwed up, she was still the queen, with a duty to do whatever it took to remove a traitor from the throne. And as a mother she should have been willing to do pretty much anything to protect Elayne from Gaebril; she was his logical next target.

These decisions, obviously, were made before Morgase knew Gaebril was dead.

After finding out that Gaebril was dead and Elayne had taken the throne, the best thing Morgase could do for her realm - and her daughter - was to abdicate. Merely by being alive she rendered Elayne's claim to the throne false. It was at this point that she should have married Tallanvor and quietly gone to live on some farm in the Black Hills. Accepting service with Perrin, on the basis that she could somehow benefit Elayne by doing so, was to presume on a role and a duty she no longer had, and - as did in the end happen - it made her vulnerable to being recognised.

And in any case she should never have come back to Caemlyn, or let it be publicly known she was still alive. Elayne and Gawyn could have been told privately, and discreet arrangements could have been made to find her somewhere comfortable (and isolated) to live, with a few servants and a bit of an income. Elayne had struggled to overcome conflicts and divisions, and Morgase's mere existence could tear open those barely-healed antagonisms.

The biggest mistakes Morgase made were that, and going to the Whitecloaks. But it must be pointed out that she had spent months under intense and repeated compulsion and that her judgement was very definitely impaired, then and thereafter. I get as irritated as anyone when I have to read her POVs, but I can't help thinking that what Rahvin did to her - the long-term effects it could have had were not unlike some form of brain damage.