I would let her stay.
Enjoy the decrease in credit risk offered by government now assuming the payor position.
Good tenants offer value beyond their cashflow.
The certainty they provide, in a business otherwise full of gotchas, let's one focus attention on higher value opportunities in business.
Lastly, judging from thoughtful advice you offer of a personal nature on BP podcasts, I suspect asking her to leave will eat at you karmically.
Stand in front of a mirror and imagine telling your favorite math teacher that you've grown up to be the kind of person who is so successful that you ask old lady tenants to leave after six years of great tenancy because their finances weakened to the point that they needed section 8 assistance.
It is a business but there is room in it to be thoughtful broadly in the way that Bruce and Michelle Fischer approach it.
The contribution you make to your tenant and your community by letting her stay will be paid forward to you in some other way in the future.
I would let her stay.
