1. I bought six-year old red ginseng.

2. I bought six-year-old red ginseng.
(Which one is grammatical?)

3. He narrowly escaped being drowned.
4. He narrowly escaped from being drowned.
(Are both the same and grammatical:?)

Sentence 2 is correct.

I'd phrase 3 differently, and I wouldn't use 4.

3. He narrowly escaped drowning. (meaning he was swimming on his own)

[He narrowly escaped being drowned <~~ This means he was with someone who tried to drown him, but he escaped.]