Here is some information that states that 'common law partners' have very little rights if the partner dies.
In particular:
And if your partner dies?
* If they haven't made a will, you won�t automatically inherit anything from them, including the family home if it's in their name or if you own it jointly as 'tenants in common'.
It would seem that his next of kin would have inherited - his mother.
On the mother's death her next of kin will inherit, unless she has left a will.
At the moment there are very little rights under common law for unmarried partners.
I think your friend is going to be facing a long drawn out battle if she goes to court, with very little chance of winning.
Legal fees will be horrendous.