I saw my 1 yr old hen had worms and I ordered some valbazen to deworm them since the Wazine 17 I was using didn’t kill the worms that they had. I checks on her and saw her vent was inflamed, infected and very stinky. I didn’t want her to suffer any more so I culled her. Below is what her vent looks like
It looks like something more was going on with your hen than worms. The vent opening is very wide and raw looking. I would suspect something like vent pecking or vent gleet, but there may have been other reproductive problems going on. During warm summer weather vents that look like that can be infested with maggots when flies are out. I would look at some more of your hen’s vents while they are on the roost at night, just to see if any others are looking like that. Valbazen dosage is 1/2 ml given orally to each chicken and repeat it in 10 days. That will kill most chicken worms. Sorry for your loss.