Legal obligation

Tenancy Types and Management

Last night one of my tenants told me she had lost a key & could I drive to my property with a spare key to let her in? My issue is that this tenant is 2 months in arrears & lied about where the key was!!!she said her daughter had misplaced it, but when I got to the property it was on the floor behind the front door!!!, so as you can imagine I was not very happy having to drive a 40 mile round trip to let an incompetent tenant back into my property!!!
The tenant said it was my legal obligation to go and let her into the property? My husband was livid and said not to go out to them,however I did not want them causing damage to our property trying to force entry! Where do I stand with regards to legal obligations to tenants if this situation arises again?