This whole area is very complex indeed. But there are some things to consider.
To start with the simple case:
"...the other has her mothers house in a 50/50 trust and then only 50% of the property can be used for care."
This is very common indeed. A married couple owns a house as "tenants in common" instead of "joint tenants".
"Joint tenants" mean that you both own the whole house jointly together (just like a joint bank account). So, on the death of the first spouse, the ownership of the house automatically passes to the surviving spouse.
If a house is owned as "tenants in common" then each person owns a separate 50% of the house and they can leave their 50% share of the house to whoever they want (normally, it is left to the children and the surviving spouse is given a life interest so that they can remain living there).
In a typical situation where a husband will die first and the surviving wife later goes into care this will protect 50% of the property from being taken to pay care home fees.
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"One has the whole house in trust and her daughter lives with her and she said it will just go to her children and they can rent it out"
This one is rather confusing. It depends a lot on how old the daughter (or the daughter's husband) are when the mother goes into care. If either of them are then over the age of 60 or are disabled then there is a "mandatory disregard" for the house anyway as there are "specified family members" living in the house as their main or only residence.
This doesn't require a trust at all (it just needs one person to be over the age of 60 or disabled).
Putting a property into a trust in this situation doesn't really seem to make much sense. Perhaps they were persuaded by some will-writing company that it would help them?
"...go to her children and they can rent it out"
This bit really does confuse me. How can they rent it out if they are living there? Something doesn't really add up about that.
I would just like to add that you shouldn't forget that relatively few people go into care homes anyway.
Today, if you are currently aged 65, then you can expect to live to 86 on average if you're a woman and 83 if you're a man (source ONS).
Of women aged 80-84 there are 4% in care homes, but this does double to 9% for those aged 85-89.
So, more than 90% of women do not go into a care home.
(the figure does rise dramatically for those aged 90+. The figure is 21%, so if you live past 90 you have a one in five chance of ending up in a care home, but a four out of five chance of not being in a care home)
The comparable figures for men are 2.5% for those aged 80-84 and 4.5% for those aged 85-89. So, only one man in twenty aged 85-89 is in a care home (and the average age of death for men is 83)
(source ONS)