I'm sorry you're dealing with your Mum having a long-term liver condition.
Mustachians seem pretty scattered, and it's possible you'll tap into someone with knowledge of Singapore's systems, but I don't think I'd count on it; moreover, you don't want a general overview, you want to know about your Mum's prospects and the associated costs. I'd guess your best bet would be to ask (her) if you can consult with her doctor (I'm assuming she has one) about her condition and its likely progression and treatments, including costs within the system where you find yourself. I know pricing in the US is generally quite opaque, but my sense is this is less true in other parts of the world.
In the US, you'd be looking at 6 figures, not 5, for a liver transplant (or perhaps more, i.e., 7) and associated costs. Also, I have no medical training but my impression is that people who have transplants typically require lifelong drug treatment to prevent the body from rejecting the transplanted organ (which, even though "similar" to the patient's, the body recognizes as foreign). All of which is just to say you're probably best off getting good information from someone who really knows what they're talking about, given the situation, rather than general advice from someone on the internet.
My best wishes for your Mum's well-being.