The law has changed since you last looked at this, Gordanus
Up to 2009, it was possible to transfer or bequeath a "life estate" in land. So Husband could leave the house to Wife for her life, with remainder over to Son.
In that scenario, Wife would only have a life estate in the house, so that's all she could sell or give away. She couldn't leave the house to someone by will since, by definition, her interest in the house would die with her. She could sell or transfer her interest to Someone, but all Someone would get would be ownership of the house until Wife died, at which point the life estate based on Wife's life would come to an end, and Son would become owner of the house. Obviously, Someone wouldn't be interested in paying much - or anything - for such a limited ownership of the House, so Wife's interest was not in practice saleable. (Wife and Son together could sell the house outright, if they were in agreement to do that.)
Life estates were generally regarded as a Bad Thing. The owner of the life interest (confusing, called the "life tenant", even though they weren't a tenant in the ordinary sense) had little incentive to maintain or improve the property (especially if they weren't living in it). They couldn't easily mortgage it if funds needed to be spent on it. Meanwhile the person next in line (the "remainderman") was in limbo — he didn't known when he could enter into occupation of the house; in the meantime he had to make some other arrangement to house himself, but he didn't necessarily want a long-term arrangement. So he might be renting for years, waiting for the life tenant to die.
The law was changed in 2009 and you can no longer create a life estate in property in Ireland. What Husband can now do is make a Will leaving the house to Son, but subject to a right of residence for Wife for her life. Wife doesn't own the house but she has the right to live in it, rent-free, for as long as she lives. She can't sell or transfer her right of residence to anyone. Sons can't in practice sell the house subject to Wife's right to live in it (who would pay money for that?) so, again, the practical way to sell the house is for Wife and Sons to agree - Wife surrenders her right of residence so that the house can be sold, in return for which she gets a cut of the sale proceeds. It's a bit easier for Son to mortgage the property, though a bank will want Wife's consent. While there's still the issue of who will pay to maintain the place and where Son will live in the meantime, re-expressing the concept so that Son is regarded as the primary owner even while Wife is in occupation does clarify people's thinking.