Feeling bad, Older tenant, Under market value

[Ian Handel]

I feel bad.  One of my tenants is in her upper 60's, she works for a temp agency and has difficulty paying her bills.  She is never late and hasn't missed a payment.  She's been living in the building for six years.  Her daughter lives with her, but her part-time work at Starbucks doesn't pay enough to make a great impact on paying the bills.

The oil tank that supplies this tenant's unit needs to be replaced.  I'm looking at a cost of about $1500-2000 for that work.

The monthly rent is $925 for a nice two bedroom.  It was raised from $900 last February.  She is well below market rent.  I am getting $1025 for the identical unit above her.  The market rate for either of these units is about $1100.  

I discussed raising the rent with her, she claims she cannot afford any more, maybe $25 she offered.

I feel bad.  On the one hand my rental should be at the market rate, on the other hand, I have a nice tenant who cannot afford to pay the market rate, not for what she has currently.  Do I raise the rent and force her out?  Do I bite the bullet and keep her?  What happens in 5 years when she can't find a job at all?