Offer to buy them a few indoor portable heaters until you find a solution. 

If heat goes out in the winter we drop off several units, so they can be placed in different parts of the house - including every room with water like kitchen and bathrooms.We also have dehumidifiers, carpet blowers, shop vacs, puddle-sucker pumps, extra hoses, extra sump pumps with battery pack, squeegees, and portable AC units ready to deploy. 

Quote from @Alecia Loveless: I had a tenant that used a portable washing machine.

The property I am submitting on this week has a hot tub,  sauna, and beautiful view.I will be adding ac, EV charger, foosball table, table tennis, billiards.  

The only 110v dryers I see online are small portable units.

In CA Public Works, they typically allow 1-3% mobilization costs.Depends on how large of a project you're doing and what the contractor is to provide, like portable restrooms or storage containers.

LOVE offering my Airbnb guests amenities like a pool, spa, sauna, laundry, picnic area, etc; without having to personally maintain those items.3.

But I wouldn’t use that portable unit. 

So, if emergencies are the use-case concern, that is one option but also portable power stations which can be used at home, camping, tailgating, etc.

.$69.99 - BISSELL Little Green MultiClean Portable Deep Cleaner - https://www.costco.com/bissell-little-green-multiclean-porta...If you are going to have pets, then this little guy is great.