Landlord advice about giving notice to tenant

[Shana Amaral]

So my current tenant told me back in september 2018 that she needed a first floor apartment (because she got sick and needed help going up and down the stairs) completely understandable so she said she was going to start looking so i followed up a month and a half later because i hadn’t heard from her and i had a prospective tenant lined up and she said she was too weak to move in her condition which put me in a rough spot since i had a lot of interest from a new tenant so she said maybe a couple more months she could start looking again but she would let me know for sure when she did. After january hit i knew she wasn’t going anywhere until winter was over. it’s now april 1st and still no word. how do i proceed? call her and ask when she is going to start looking again because i feel like i’ve been pretty generous in letting her stay longer when i had someone to go up there and it’s been on hold for them. legally how do i say nicely that she needs to start looking and how long is the minimum amount of days to let her find something and does it need to be in writing? and what if she gives me a hard time? - sorry first time landlord here