AIBU to refuse a tenant's vulnerable guest staying in my HMO?

Vointoffiew.
You are obviously a landlord ( from your comments ) have you given your property to the local council, as you suggest OP should do??

give the poster your address and let the woman move in with you...sorted

So take her in then. Sure you've got space for an airbed on your bedroom floor.

Yes but you have a bedroom, why wouldn't you share it? If you wouldn't, why do you think they tenant should be pressured into doing so? And why do you think the other tenants should be pressured to share their kitchen and bathroom with an extra person?
Telling the LL just to get the help the person needs from adult social care or shelter just shows you really don't understand how thin the safety nets are. They're full of gaps for people who have full rights for support, let alone people who are here on the basis that they are self funded.

Good that you’ve let tenant know you’d evict him if he keeps letting her in. There needs to be a real consequence for him, both that he can quote to others and to stop him from rolling over when pushed.

Otherwise it’s ‘everyone against the officious landlord’ from relative and her friends’ perspectives - who clearly don’t give a shit about his preferences, your other tenants’ interests or any consequences for you.

Whether or not you find it hard to believe it is the case

Just another NIMBY!

Makes her more vulnerable

Ive suggested what I'd do. She isn't in my HMO. When people like this have been, I've taken the steps I suggested to OP. They arent there any more.

If she’s a substance abuser, which seems all too possible, would you? If she’s disrupting the lives of other tenants? I’ve lived in a shared jouse (not strictly speaking an HMO) with an alcoholic who had mental health problems and it was absolute misery. You never knew when he was going to kick off or what you’d be coming home to.

Oh stop it!

Why does her right to a home trump the right of the OPs tenant to have a room to himself?
Why aren't you offering to share a room with this person, or pay for her to have somewhere to live?

Even though she caused damage and complaints from her other tenants?
All for helping people but not if they don't help themselves too. Behaving like this is unacceptable. The OP has a responsibility to her other tenants too, including the one who let her stay who now wants her out.

Unfortunately you are right in that the tenant is responsible for their visitors. If you can be assured that he is doing all he can to not let her in, including changing the locks, then all you can do is advise to ring the police. Maybe fit a doorbell camera too linked to your phone so you can see things for yourself. If the tenant is scared of repercussions (he might be vulnerable to cuckooing), can you offer them a place on one of your other HMO’s as long as you trust them not to repeat this? Or would you rather get rid?

Edited to add that the Council might be useful in this situation as they have resources that try to prevent cuckooing even of owner occupied properties. Once they’re in and using substances it causes a whole heap of other issues.

I told her what I have done in the past.

Ok don't help her then. It's just been my experience that she's more likely to stay away if she has other options.

You shouldn’t be talking to the friends. That crosses a line into interfering in people’s personal lives - even if the tenant would like you to do this on his behalf.

Otherwise, you’re right. Draw a firm line and stick to it. Otherwise, Council aside, you’d surely be breaking your contract with the other tenants, who signed up to live in a house of four tenants, not a hostel for variable numbers of vulnerable, unpredictable people.

No you have only TOLD her what you would do.
But I really think you have no grasp of the situation here.

No need. He's happy with a roof over his head until he gets somehere else.

She is to the landlord but I think you are being intentionally obtuse. You've chosen the hill you want to die on, and nothing is going to get through to you.

As have I.
The criteria for supporting people under NRPF are extremely strict. I worked for a charity for those who were street homeless, we had a mixture of grant funding and public donations. We had to evidence in the books where people who were NRPF got food parcels, where the funding was from (donations from the public) as we would be going against the terms of our grants/contracts if we used any public funds.

The only way people who are NRPF can be housed without paying for it themselves through wages/savings is if there's a human rights case to be argued, and that's usually very temporary or someone gives the house for free (there's a tiny number of churches that have done this)

Obviously people can be NRPF and claiming asylum in which case they can get asylum specific accommodation during the claim but I don't think that's the case here.

Basically, there's whole categories of NRPF people LAs don't have any duty to provide with housing at all.

There exist some charities who provide housing for people in this situation, without being able to claim any public funding towards it. If none of these charities have anything available, and I assume we all know we're not exactly in an environment of abundance for the sector right now, there may not actually be anywhere such a person can be referred to. They're going to be housed unofficially or not at all.

You could still come in to do his meals and clean the house? Maybe he will let you be a tenant.