Questions & Answers about Hún kom grátandi heim eftir samtalið.
Kom is the 3rd-person singular past tense of koma (to come).
So:
- ég kem = I come
- hún kemur = she comes
- hún kom = she came
It matches hún because the subject is she.
Grátandi is the present participle of gráta (to cry / to weep).
In this sentence, it means something like:
- crying
- while crying
- in tears
So kom grátandi means she came in a crying state, or she came while crying.