My son and his family could end up homeless

CAB or an hours free advice from a solicitor ?

Absolutely he needs legal advice, due to Coronavirus Legislation, tenants have more rights at the moment.

A great deal will depend upon the lease that was signed by both parties as to whether he can regain possession, even through the Court process. Do you know the terms of the lease?

realistically i think he would be lucky to regain possession this year.
there is a great backlog, and it usually takes at least 6 months, and is very expensive as bailiffs would be needed eventually for tenants who refuse to budge.
why is he in airnb, that's expensive long term.
is he single. why doesn't he rent a room in a house.
are there any relatives where he could stay.
look on shelter website. he needs to get the paperwork in asap re eviction.

just seen, title mentions and family.
how many. could go local authority but unlikely they will offer anything, except may have local advice.

He can't legally evict them at the moment because of covid

As it will cost him thousands to get his tenants out, and many months, they may leave if he offers them some money to go.

There is a gov helpline he could try first.

I think tenants have unfair rights, they can delay eviction for up to a year.

Lost my last post for some reason.

My son is married with 2 children aged 10 and 7. There are very few rental properties around which is why he’s in an Airbnb. The one they were in this month was the size of a rabbit hutch. They have moved today to another one. Additionally nearly all their possessions are in storage which is another huge expense.

Sounds like your son will benefit from two websites.
Look on Facebook for the "UK Landlords Support" group. They are an absolute minefield of landlord queries & how to get your property back. Secondly, he should explore joining the NRLA. It's a small membership fee for endless support & legal advice to Landlords.
At present he could serve a Section 8 for non payment of rent or a Section 21 for a repossession. If he is owed rent he can go for a Money Collection Order (MCOL) he could also, long term, get a County Court Judgement (CCJ) against the tenants which will really impact on their credit record & mess them up.
Right now evictions are taking, by law, at least six months due to C19 but if he acts fast that will fly by. The courts are seriously backed up but if he's got all the legal paperwork in place, an eviction should go through. There's a long list of legal obligations and certificates: EPC. Gas Safety Certificate up to date, How to Rent booklet, deposit with a Govt recognised deposit system, current Electrical Safety Inspection report etc. Check out the GOV.UK website for more advice. Just enter "tenants" or "tenancy law". Something like that will bring up loads of govt advice/rules/regs etc.
Good luck. Don't delay. Get the process started. Some landlords, like many others, are having a tough time right now. They have mortgages to pay but no rent coming in to pay it. I have good tenants but some (proven) unscrupulous tenants are taking advantage and screwing over their landlord.

As an afterthought ... There are still flats to rent for your son and family. I know this because I was looking on line this afternoon in my local area in Devon. (As a landlord I keep up with the market!) We also have a benefits system in the UK which might help with rent etc. Citizens Advice might be helpful for all sorts of queries.

He can't serve a section 8 or 21 atm because of the laws surrounding covid. He needs to move in with the OP or other family if he cannot afford alternative accommodation

does he have landlord insurance? He might get some help from that

I can visualise that many will be looking for accommodation by the time this virus has ran its course. There'll be so many unemployed facing losing their homes, it doesn't bear thinking about.

Just search "Gov.uk evictions."
All the current rules are there. S8 or S21 is currently six months but can still be served now. Read up on it. Knowledge is power.
I hope us grans have helped put your mind at rest a bit? There is advice out there you just need to know how to access it.

NRLA.org.uk. Look them up. They can help.

www.gov.uk/government/publications/covid-19-and-renting-guidance-for-landlords-tenants-and-local-authorities/coronavirus-covid-19-guidance-for-landlords-and-tenants

It can be served now but only for a very limited number of reasons such as anti-social behaviour, the death of the lease, domestic violence where the abusive partner refuses to leave.

Rent arrears have to be more than 9 months.

I’m afraid the Landlords’ Association has reports of landlords that are now homeless whilst their tenants live rent free. Your son is in a terrible place with very little he can do legally.

He could ask for a mortgage holiday to alleviate his financial problems or he could offer the tenant money to move out.

It is so unjust and unfair. The law very much favours tenants.

he won't be able to get housing benefit as he owns a house.
also i think has to be back in uk for at least 3 months before can claim any benefits.

Get advice! Do some research based on advice from Gransnet. Don't listen to naysayers. Knowledge is power.