Evicting tenant after buying 2 family in MA

[John Shea]

Looking for some advice.  

I will be closing on a 2 family tomorrow afternoon in MA.  I will be occupying the downstairs unit, and the upstairs until has been occupied by the same tenant for 6 years on a month to month basis.  I went into this deal very excited knowing that the upstairs unit would already be rented out by what I thought was a reliable tenant.  I also met this tenant on two occasions and she seemed very nice and kept a very clean apartment.  She also told me she has been living there for 6 years, so did not think to question this.  

I just received an email from the seller's agent that read as follows:

"The owner has asked me to reach out to share the following message with you.  I spoke with the upstairs tenant (name) yesterday.  She will pay the buyer half the rent ($525) for August on Monday.  I will work out an agreement with (name) to pay me the money she owes when she gets a new job.  She's between jobs right now.  I'd like the buyer to know that (name) has been a fantastic tenant for years and I recommend her as a tenant.  She's been in similar situations twice before and managed to get a new job and catch up on the rents."

I am wondering if it would make more sense to generate a 30 day notice to quit immediately due to new landlord and prevent having to deal with any headache.  What steps should I take to avoid her from squatting in this property?  I also found it odd that she is offering to pay on Monday of next week Aug 20th, 5 days after closing. 

Thank you for your help!