Dad recently passed away and Mom has always been bold with her words but now she's being mean and rude not only to me but to others. Advice?

Really, who knows why your mother is acting ruder than normal, unbearable & controlling now that your dad has passed? Since she's now in charge of her entire life, she may feel pressured to BE controlling since there's nobody there to help her anymore. The loss of a loved one after a whole life of being together can take a huge toll on someone and their behavior can and often does change as a result. Anger is one of the stages of grief, so that may be what you're seeing, more than anything else.

If you don't see her all the time, perhaps you're missing some cognitive decline in your mother as well. Has she been to the doctor recently for a physical? Or are you relying on HER to tell you that she's in 'good health' and perfectly capable of caring for herself? When an elder starts down the road of cognitive decline, you'll start seeing many odd behaviors you haven't seen before and you won't know WHAT to make of them. Here is a list of what to look out for:

Mild cognitive impairment (MCI)

Overview
Mild cognitive impairment (MCI) is the stage between the expected cognitive decline of normal aging and the more serious decline of dementia. It's characterized by problems with memory, language, thinking or judgment.
If you have mild cognitive impairment, you may be aware that your memory or mental function has "slipped." Your family and close friends also may notice a change. But these changes aren't severe enough to significantly interfere with your daily life and usual activities.

Mild cognitive impairment may increase your risk of later developing dementia caused by Alzheimer's disease or other neurological conditions. But some people with mild cognitive impairment never get worse, and a few eventually get better.

Symptoms
Your brain, like the rest of your body, changes as you grow older. Many people notice gradually increasing forgetfulness as they age. It may take longer to think of a word or to recall a person's name.

But consistent or increasing concern about your mental performance may suggest mild cognitive impairment (MCI). Cognitive issues may go beyond what's expected and indicate possible MCI if you experience any or all of the following:

You forget things more often.
You forget important events such as appointments or social engagements.
You lose your train of thought or the thread of conversations, books or movies.
You feel increasingly overwhelmed by making decisions, planning steps to accomplish a task or understanding instructions.
You start to have trouble finding your way around familiar environments.
You become more impulsive or show increasingly poor judgment.

Your family and friends notice any of these changes.
If you have MCI, you may also experience:

Depression
Irritability and aggression
Anxiety
Apathy

It's the last 4 signs that you may be noticing with your mother: depression, irritability & aggression and anxiety. Keep an eye out for her losing her train of thought while talking to you, or using the wrong word (saying refrigerator when she means purse), and things like that. Sometimes MCI is exacerbated when a spouse dies or another drastic life event transpires.

Things may settle down for her after a while, you'll just have to wait & see. Maybe plan a visit to see how she's doing/acting in person, and if there are any significant changes you note while in her presence.

My condolences over the loss of your father. Wishing you the best of luck trying to figure out what's going on with mom, aside from general grief which can be quite long lasting and intense.

My take? She is upset and even angry that her husband has died. A whole mess of emotions and it’s overwhelming. She has no way (to her, anyway) to express what she’s feeling, so she’s lashing out.

My mother did pretty much the same when her mother (my grandmother) died. She’s never been able to process tough emotions. Grandma was 94, had severe heart problems, and doctors had told mom she didn’t have much time left. Grandma was exhausted and was ready to go. Mom tuned it all out. When grandma was dying, Mom insisted “I thought she’d have at least five more years! I never saw this coming!”. They weren’t even all that close. People have their own ways of dealing with pain, grief and sadness.

For awhile she was just snapping at everyone, like since she felt crappy, everyone else around her should too.

First I'm sorry that you lost your dad. Second, be glad that you live 1 1/2 hours away from your mom and that she is still able to live on her own and is in good health. That is a blessing for sure, as at least you don't have to see her often. And if she gets to be too annoying, you have the luxury of not answering your phone and just letting her calls go to voicemail.
As unhealthy as her attitude is right now, it may be her way of dealing with her grief, but that doesn't mean that you have to tolerate it or put up with it. It's probably best to just keep your distance and monitor your calls, so you can properly grieve your dad, without mom's attitude interfering. I wish you the best.