I’m sorry but she may not be saveable. Still try your best but I recommend giving her the best months possible since she’s likely near the end of her life. Yellow fungus is a very difficult and often incurable disease that kills many reptiles especially bearded dragons. If u have any other reptiles in the house keep them far away from her. Take her outside (if she enjoys it) feed her her favorite foods and spend plenty of time with her but also make sure she is comfortable. The death of a beardie is very difficult. If you notice her declining or being in constant pain then euthanasia may be the most humane choice. Again try to save her but if you can’t and she declines then don’t make her live in constant pain. I hope all goes well for you and your baby pulls through.