I'm so sorry this is happening to you both.
At fourteen, she doesn't have a chance, and honestly, lymphoma is deadly pretty much no matter what.
Rather than doing flips and trying to fight it off with things that could in fact make her really uncomfortable, I would just make sure she is happy as she can be and as comfortable, and when she is about not to be, let her go in good time. Things like turmeric may fight cancer, but not enough to do anything but cause her diarrhea and the ensuing misery and dehydration.
If I thought there was anything that would truly make a difference, I would tell you to try- but the fact remains, at fourteen, dogs don't have much to fight with, and their systems are fragile - and if the lymphoma is evident, it has already invaded her internal organs. Please just keep her comfortable, and give her whatever she can eat and digest, without adding odd things. It just isn't worth it. Try and enjoy the time you have left, and be at peace. That is what she would want, and that is a dog's lesson in the end.