Selenium is already in her food, but many use scrambled egg to add more selenium which helps in vitamin E uptake. Sardine, tuna, and other things contain selenium, but only a little is needed, and too much can be dangerous, why we usually don’t recommend a selenium supplement.
Any b complex is fine, regular, b 100, or super b complex. It might take some time, days or weeks for symptoms to improve. Yes, give her the b complex and E daily for a few weeks to see if they help. Helping them get enough to eat and drink is very important, and might need to be done 2-3 times...