Tenant moved out and subleased to two subtenants-No lease with subtenants

[Banu Sho]

1) My house in LA County was leased back in 2017 with the contract. The lease was then never renewed so it became month to month. The tenant left in 2019 subleasing the house to two subtenants who pay rent regularly but there is no contract with them. Can I make a new lease with the two subtenants and raise their rent? It is a single-family home (not subject to RSO) but has two kitchens and two subtenants staying. Rent is below market. How can I raise the rent and have them sign a new lease?

2) Second subtenant has complained of mold in his kitchen that I need to get fixed by removing the mold and replacing all cabinets in the kitchen.

How do I handle the case? Should I wait to make a new lease till the mold problem is solved? What is the waiting period for a new lease and rent raise?