Joint Tennants transfer to Sole

Hello. My contract is with Mr & Mrs. Mrs has informed that Mr has left and she would like to stay on with children. She is eligible for support which will cover the rent and things between them are reasonably amicable.

They are really good tenants and I would like them to stay on - should I change the contract/deposit into her sole name or leave it as he hasn't approached me to be removed etc. Any advice I would be really grateful.

Thanks