So the cost is lower than you might think.If you are able to install something like this:Handicap Accessible BathtubIt may be a win/win.If/when the day comes that they move, advertising that you have a handicap accessible unit may get you tax benefits and other tax preferential treatment if you are working with county agencies trying to place handicapped folks in need.

It requires weed n feed treatment, overseeding and watering however I'm wanting to gauge how or when anyone in the BP community would address this with the tenant.

(D) Not more than two accessory dwelling units that are located on a lot that has an existing multifamily dwelling, but are detached from that multifamily dwelling and are subject to a height limit of 16 feet and four-foot rear yard and side setbacks.(2) A local agency shall not require, as a condition for ministerial approval of a permit application for the creation of an accessory dwelling unit or a junior accessory dwelling unit, the correction of nonconforming zoning conditions.(3) The installation of fire sprinklers shall not be required in an accessory dwelling unit if sprinklers are not required for the primary residence.(4) A local agency shall require that a rental of the accessory dwelling unit created pursuant to this subdivision be for a term longer than 30 days.(5) A local agency may require, as part of the application for a permit to create an accessory dwelling unit connected to an onsite water treatment system, a percolation test completed within the last five years, or, if the percolation test has been recertified, within the last 10 years.(6) Notwithstanding subdivision (c) and paragraph (1) a local agency that has adopted an ordinance by July 1, 2018, providing for the approval of accessory dwelling units in multifamily dwelling structures shall ministerially consider a permit application to construct an accessory dwelling unit that is described in paragraph (1), and may impose standards including, but not limited to, design, development, and historic standards on said accessory dwelling units.

They will ALWAYS ALWAYS ALWAYS end up wanting a favor of some kind that puts you in an awkward position, and they will expect special treatment because they are your pal. 

Most states allow tenants to leave any day of the month as long as they give notice 30 days prior to vacating, and the landlord is required to prorate rent through the day of departure.Your tenants failed to pay any prorated rent for the month of January so I would not give them any special treatment.

Plus, we can price the service to include treatment of all pests (including BB) for one monthly fee. 

If every month they are paying late (Not entirely a deal breaker for me, I have one tenant who pays on about the 21st of each month, they have been my tenant for 3 years) but lying about why they are paying late, then Id be more in line with @Roy N. suggestion of starting the eviction process.However I will say that the bedbug thing possibly complicates this slightly on a couple different levels. 1) if they move out...I really suggest getting the property treated for bed bugs, and I recommend the heat treatment process for this.

Repeated symptom treatment usually leads to major, more costly failures.

But it is actually an LLC that has elected S Corp tax treatment.5.)  

Capital gains tax treatment does not apply to flips