Obstruction - to what base?

[WestMichBlue]

Will you protect an obstructed runner to a base beyond which the runer attempted to advance to, if they are not put out?

Lets say a ball hit between the outfielders, a potential double. B-R and F3 collide and B-R goes down. B-R gets up, looks at 2B, but F8 has ball and is throwing back to infield, so B-R returns to 1B.

Do you call time, and send B-R to 2B? Do you attempt to judge the athletic ability of the runner to determine if they would have made it without the obstruction? Ie., Wheels Wanda would have make it easily, but doubtfull if Lumbering LuAnn had a chance. Does it make a difference if Wheels does a flip and is instantly on her feet, but LuAnn is slow to pick herself up?

WMB