Will social services help? Nasty behavior from 84 year old mom -- is it illness or personality?

Boyfriend's mom, who is 84, makes up lies, threatens us with police (while there actually is a case open against us right now due to something she claimed against us) and social services, she claims that we are aggressive and she's afraid of us. Mom lives with boyfriend, she has no other family here that would help. I have my own place but I spend a lot of time at boyfriend's and have witnessed some crazy stuff.

A few months ago, a suggestion about her living arrangements was made while boyfriend and I think about our future together, and that made her completely flip out and that's when her false accusations against us started.

Prior to the time when she became furious about our living arrangement proposal, there have been times when she left the stove on and gas was leaking. Also, she would say that she had fallen and when we said we'd call the ambulance because she couldn't get up, she sprinted up like an athlete. We thought she was faking it for attention because this behavior was accompanied by her being pouty, but now we are more concerned because we are hearing from people that she told them she had fallen. We don't know what's true, we have not actually seen her fall. Mom said one time she couldn't get off the toilet and she was banging on the door and nobody came to her rescue. We don't think that happened. She has a panic button she can press for help but she never wears it and uses it to call on her son as if calling a butler.

It's very stressful, the false accusations and the fact that we don't know if she does have some falls or accidents because she will say she fell to get attention but when we want to seek help for her she jumps up and refuses to have 911 called and since there was nothing visibly wrong with her, we did not call 911.

Mom is 84, lives with her son who is at work all day. She is not ill, she takes daily long walks, is able to shower, groom, feed herself, she does not need help with anything other than communicate with people other than boyfriend and me because she doesn't speak English.

Mom has been telling weird stories since I've met her. She'll talk about stuff that supposedly happened like 20 years ago when she lived with her son back then, she wasn't being fed properly and lost a lot of weight. She likes to play the victim, she uses foul language with people close to her but she's proper when talking to people with whom she feels she should not cuss with. When we confronted her about lies against us, she started turning attention to herself, her legs hurt, she can't remember, she's old, we don't understand - pretty much anything to change the subject.

Because her hate toward us seems to intensify and the accusations are becoming more frequent, we feel we need to do something - but what can we do? We thought about calling social services for resources, any type of assistance but we don't want to create more problems.

I thought about dementia, but she seems logical at times, she remembers phone numbers, she calls people from memory, she doesn't use stored numbers. She shops and pays for her stuff and is able to count money and pay the proper amount. It's out of the question to suggest to her she be tested, she will probably freak out as she has already pointed out that "yeah I'm old and not right in the head, right?" We looked at dementia symptoms and maybe one or two might fit a little bit but then that kind of stuff happens to me as well. I used to think that she's just a nasty person and she truly does seem vindictive, angry, self-centered, but I'm really wondering now if there might be an underlying issue.

What would you recommend? Can she be tested without being told what it's for? Maybe that would help us in the way we deal with her and find her proper care? Should we contact social services? Don't know where to begin.