Once she paid rent and moved in, she became a month-to-month tenant, regardless of the length of time she stayed in your house. As a month-to-month tenant, she is required to give you a 30-day written notice of termination, and she is responsible for rent during that 30-day period, whether she stayed there or not.
A landlord has a legal duty to make appropriate repairs and to do so promptly once notified. The rules governing landlord entry into a rental unit are stated in California Civil Code Section 1954. This statute says that a landlord may enter only during normal business hours and only for a legitimate reason, which includes repairs, and only after giving 24 hours written notice to the tenant.
The cost rose a lot following the pandemic. And some of that was supply chain issues that really increased the costs, and then they didn't quite come back down. And now tariffs are also impacting some products. These costs are part of the reason the amount of new rental housing stock is shrinking.