Shalom, I'd say to get a G36E Valkyrie, G36KE, M6A2 SRT, or M4 Super 90.
Reasons why:
G36E Valkyrie and G36KE have great accuracy (especially with a modded scope)
and their damage is just gruesome for your target.
M6A2 SRT, judge it yourself, i've heard it's beast, I never had any hands on play with it though.
YouTube - Combat Arms: M6A2-SRT Review (Baxstar)
M4 Super 90, it's basically the cheapest gun in Combat Arms (skillfull wise)
It's Damage, RoF, and range is amazing, and because it's a shotgun, you can shoot and reload as you go. Although you may get rage kicked, it's still worth it ey?
You should also stock up on some GP / XP Passes, about 2 40% GP and XP passes.
as well as up to 2 Black Hi-Sec Keys, 2 Renewal Kits, or 2 GP Cases.
Live Long and prosper, good luck.
Sorry about your grandmother Mouzie.