Stock up on Baked Beans.

I will play `Master of Puppets` on my quitar.

I have yet to find the Facebook you are talking about...

So I guess it is here I must post...

I would grab as much food and tools as I can and head for the strongest building I know then I would plan for the future within its reasonable safety

I'd be going what's a "Conjuction of Spheres?"

Alright, here is another way too realistic take on this whole ordeal:
So, the conjuction of spheres brings weird monsters that can withstand ridicoulus amounts of punishment if silver is not used, and also magic.
Whilst in the witcher games you are told that steel is useless against them, Geralt can apparently swing a sword hard enough to at least do superficial cuts, so a good ol' 5.45x39mm AP will do the trick, albeit more rounds might be needed compared to the standard bloke in ballistic vest. Stuff goes through cinderblocks, so don't go "bUt mONsTeR StrONk!!!" on me.
Larger beasts might be a problem but 7.62x54mm and .50 Cal would be the solution for those, and for the gigantic ones that are made out of solid rock, ATGMs and the like are the answer.
All in all, whilst the initial days after the CoS event would be hectic, the military would eventually come on top of the situation and handle it. Like it's supposed to.

Me on the other hand... would be F'd no matter what. If a monster spawns in the apartment building I live in, then that's it, me and my family are goners. Otherwise we might be able to close all windows and doors, get down all the shutters, and tape enough towels, rags and paper around them to muffle any sounds we make, then stay REALLY SILENT.
Once again, I live in the capital, so liberating the city would be first priority for the Gov's interest, meaning we would need to survive for just a couple of days, a week at most.

Bonus activity: Take all my grandma's silverware, and make improvised weapons with them. Might not be a witcher's silver edged meteorite steel cored beauty, but it will get the job done with at least small fry like drowners or harpies.

I buy a silver sword and try to learn magic

"First and Main condition: the part of my home need to be destroyed by fallen tree! Then my son and I will drive to the shop to buy all necessary materials to fix the broken part of my house. In the store we will find some new friends and of course enemies. When monsters will start to swarming city and nearest villages all people in the store will start to baricade doors and windows as much as they can. But some monsters will break through the barricades. Some good men and women will be killed, at the same time part of the survivers will try to break out of this goddamned city to find help. My son and I will be among them. All will be ended in automobile where I find myself with revolver in my hands without bullets waiting for the monster that will end the suffering..."
Something like this, of course this is only my own assumption and all thing may went in other way :)

Live out the rest of my days in my underground bunker

1st thing: I'd start smelting anything silver into buckshot and get to reloading.

If I survive long enough, I'd be organizing with the community to better defend as much of our area and resources as we can. We'd want to learn what new beasts we can live with, which ones are tasty, and how to keep safe from the rest.

And, as many have said, see if I or any immediate family members have a knack for magic and study.

I go on a wanton quest of self-interest against better judgement, where I predictably end up in a predicament and hopefully get rescued by someone adequately skilled who proceeds to scold me for my foolishness. Or, more likely, I end up getting eaten by ghouls.

i have no idea what that is , can i win so i can check it out?

Legs, and the monster I sing, who, forc'd by fate,
And haughty humans' unrelenting hate,
Expell'd and exil'd, left the versal shore.
Long labours, both by lake and land, it bore,
And in the baneful war, before it won
The night's realm, and brought the full wrath upon
Its banish'd gods restor'd to rites obscene,
And settled in deep dark waters unseen,
From whence the race of torment'd drowners come,
And the long glories of the monstrous some.

I'd open a shop selling overpriced equipment and buying treasures from overburdened adventurers at a huge discount.

I'd try to find an easily defendable and well hidden place to try and have enough time to study the new things coming in and have at least a vague idea of what is going on.

Woe is breaking on our shore
From highest peak to darkest depths
Our sharpest minds search lore
While our strong and gifted face the horde

May we find each other again
To twist our fate and endure the trials
May we find each other again
With sharpened swords and shinning skills

My silver melted and forged anew
I fight with skills that shine with the arcane
Thru darkest night and morning dew
I fight with my life on the line and new scars obtained

May we find each other again
To twist our fate and endure the trials
May we find each other again
With sharpened swords and shinning skills

Our wounds heal and our bones mend
Soon the fight will come back to our homes
With experience so dearly earned the beasts we will rend
To return with blood from beasts who roam