Hi, I stayed in Hostal Chelo for 5 days in May and would highly recommend it. I've been meaning to come back to the board and post...anyway, it's nice, quiet. I think you will feel very safe inside the hostal. The street outside also felt very safe to me; it is small, and busy most hours of the day and night with ordinary people doing ordinary things. There are a number of nice, inexpensive restaurants near the hostal and it's easy to get around either on foot or using the nearby metro station.
The street across Gran Via, about 200 yards from the hostal, the road that leads down to the area called Sol, is a place I (a woman) wouldn't go alone after midnight and I'm not sure I'd feel safe there after about 10 pm. But during the day it's fine.
I don't know anything about hostal Lopez.
asheaves