The women and children are either back home or, often, in huge refugee camps in countries bordering the ones they’ve fled from. The journey to reach the UK is long and arduous and full of risks, it will involve a lot of walking, being smuggled into the back of trucks, crossing water in dinghies. The people who facilitate these journies are criminals smuggling people across borders illegally, many people get scammed. You have presumably seen the news stories about people being found dead in the back of lorries or drowning due to a capsized dinghy. It is dangerous for anybody but women, children and the elderly are more vulnerable than young men. Women in particular will be more vulnerable to being trafficked into the sex trade whilst they make the journey or to being sexually assaulted by the criminals they would need to collude with to cross borders. It’s still a dangerous journey for a man but not as dangerous as it would be for a woman or child.
Once a person has claimed asylum they are able to apply to have their family join them, so it is generally safer for a family to send young man to make the journey and for him to then apply to have his family brought over safely and legally, via a normal plane or ferry, than for them all to attempt to enter the country illegally to claim asylum.
In terms of our homeless population, there are shelters and other types of emergency accommodation available for people who are on the streets. However, they will almost all have a strict no drugs and no alcohol policy and anybody in breach of this won’t be able to stay. Unfortunately the majority of people sleeping regularly on the streets have issues with addiction and as such aren’t eligible for accommodation, this is of course a problem in itself and I agree one that needs addressing, but it’s not as simple as just saying why isn’t help and accommodation available for people who are rough sleeping.