seeking advice on a good stroller/car seat combo for mother in law

My mother in law will be watching our baby 3-5 days/week so I want to set her up with a stroller and car seat combo. We have the uppababy Mesa car seat which unfortunately doesn't pair well with non-uppababy strollers. Rather than spending $600+ on the Cruz and an additional base I'm considering buying her a new car seat and stroller. Any ideas on affordable but high quality one? I was thinking Britax b agile w/ Britax seat. I'd like stroller to be fairly lightweight as she is 56 with some elbow issues at times. Tia!