I am putting in a sump and grinder pump in for a basement bath and laundry. I was wondering if I could use the 2" vent pipe from the pump package for the washer and bathroom vanity drain. Any thoughts? use a 3" vent ?

No! The holding tank vent MUST be a dedicated vent to the roof. The holding tank vent doesn't operate like the vanity vent. A house vent breathes in to relieve the suction caused by discharge running down the drain pipes. A holding tank vent breathes both in and out. It breathes out when you flush a toilet and the discharge hits the tank and it breathes in when the grinder pump lifts it up and discharges it into the sewer. Stay with the 2" vents unless the holding tank instructions say otherwise. Having said that, if local codes allow you can save yourself the hassle of running a vanity vent by installing a cheater vent,(AAV),(see image). Good luck, Tom

Speedball I am going to vent through the roof my question is can I drain anything into the vent pipe? Wet vent? The pump package is 2" pumpline 2" vent line.

Bill, This doesn't tell me too much.
"I am putting in a sump and grinder pump in for a basement bath and laundry" What fixtures are you installing. What is the brand and model number of the pump and tank. You say the grinder unit has two vents. I'd like to look up the specs on it.
Since every fixture that has a trap must be vented you may revent the washer vent back into the vanity vent and if you're planing on a shower you may wet vent that back into either the vanity or the washer drain. Good luck Tom

One 2" pump line and one 2"vent line one 4" inlet. pit viper PSEM40 4/10 hp sewage. looking to avoid breaking more concrete. closet and shower will be in the slab (4" inlet). Would be easier to drain washer and vanity into the 2" vent. I will put the in the slab (4"inlet ) if you think it is best. I assumed the 2"vent line would still work as long as the pipe was not full. Thanks for your quick resoponse.

"One 2" pump line and one 2"vent line one 4" inlet." Please explain pump line vs vent line. This vent line, does it come out of the holding tank and the pump line, is that the discharge line from the pump to the sewer. I'm trying to visualize your set up but can't locate a drawing on the grinder pump unit.
"Looking to avoid breaking more concrete. Closet and shower will be in the slab (4" inlet)."
Are you saying the shower's tied into the 4" toilet line with or without a vent. i realize that you have this all in your minds eye but I'm setting here in Sarasota trying to drag details out of you. My problem is I don't know which pipe connects to what. In plain english. How many vents does the grinder unit have? Is the shower vented? Is all you have under the cement a 4" toilet line and a shower rough in? If the shower's indeed vented from under the floor,( and I'm not too sure that it is ) is it your intention to set yourself up for a shower back up by discharging a washer into it? If all you have roughed in is a toilet and shower then you may tee off from the shower vent, (if you have one) to pick up the vanity but the washer discharges with way too much force to dump it into a drain line with a outlet as low as a shower drain. The washer should tie in downstream from the shower. Regards. Tom