Thanks for clarifying the cultural considerations--that does make a difference.
This seems to be a situation where you've hit on a solution that seems to be working for everyone, but it's the THOUGHT of his being uncomfortable that worries you and your mom. What if you were to spend some time and money fixing up his office sleeping space so it's more comfortable for him? Put in a fold-out bed or a sleeper sofa, maybe a TV? From what you describe, having him come home will be potentially dangerous for everyone.
I'd have a lot of other suggestions for your mom if she were living in the US or the UK, but I have no idea what kind of women's services there are in your country. If there are any, I'd suggest putting her in touch with them. At some point it sounds as if you may move away, and it would be good for her to have someone else to call on for help.