Upd.
In-laws collected their rent for the last month of July (they are supposed to vacate on 31st), and ta-daaaa - tenants took their security deposit OUT of that check. WHAT THE F%$%#? I think in-laws are just going to close eyes on that IF they move out on said date. But who does that?????
That is eviction notice time! (for non-payment0 I would repeat with the full normal eviction notice, too, asap. In laws can take them to court for arrears on that, as long as they pay over the security deposit in good faith. This way, they need to leave the place in good shape.
And, lots of people try this. It is one reason why professional services here do not make the security deposit a full month's rent, but some other smaller number, so that it is clear that the final month's rent is owed.