ownership and insurance

my wifes grandfather passed away recently in Los Angeles. He never created a will but thats a whole different story. One thing he had was a old Harley davidson that was registered under my wifes mom's name and his. After the passing she asked for the bike. The widows daughters got involved and it got rather ugly. They demanded that she not only supply the pink slip (not a problem) but also proof in insurance (it hasnt been registered or insured in decades) before they will allow her to take the bike. Their arguement is since the bike pink slip had not only my wifes daughters name but also her fathers name thats the widow assumes responsibililty for the bike...seeing that it is not registered and will be removed from the premise by tow truck I dont understand their concern