I wouldn’t touch it. Call it stubborn pride if you want, but a rich person trying to toss you almost a grand because she can and she feels bad for you is goddamned demeaning. It’s not like she’s trying to save you from starvation or home forclosure or something. It’s car repairs. Put it on credit and get a better handle on your business.
If I were in your shoes and I took the money my only question would be which person has less respect for me: her or me?