Depression can be hard to treat. Even with the best healthcare, because you're not dealing with the body as much as the mind; the brain itself, although being a physical aspect is still very mysterious to modern medicine to this day. At least, from my perspective, a lot of treatments are given on a trial and error basis. Sometimes they work, sometimes they don't. Sometimes when they do work, they backfire with added complications and side effects.
I don't know what to say now about this, so I'll just say I wish them peace, and I give my condolences.