More common is a flat monthly utility reimbursement fee which removes much of the complication.  

Pay the bill yourself, then reimburse yourself by charging the tenants based on a formula.

@Oscar Menendez  The contractor should reimburse you if he was neglectful, which it sounds like he was. 

looking to meet others involved in the Green Healthy home certification process I see i can get up to $6300 per multi Family property reimbursed to be Green Heathy Home certified and know Rents are higher in certified buildings. spending a little to improve properties seems to generate  30%  Instant appreciation  so let's meet up it's time to rebuild. connect and suggest times to meet or just Zoom? 

The leaving tenant should look to the remaining tenant to get reimbursed not you.  

Likewise, if / when 'tenant C' had moved in, they should have paid the tenant that stayed for 1/2 of the security deposit to where they both have some 'skin in the game' to maintain the unit, reimbursing her those funds.  

Since I provide lots of business to my cleaners they take care of that stuff for free, I only reimburse supplies.

However, I've watched several clients get burned after move out though because of their inability to get inspections scheduled or reimbursements granted for move out damages.In theory, I agree with everything OP said though.

The Lender will expect you to get started and then be reimbursed. 

The rub is youll have nobody to look to for reimbursement​ if the sober house converts to a heroine den mid tenancy.